US20100070466A1 - Data transfer techniques within data storage devices, such as network attached storage performing data migration - Google Patents

Abstract

A stand-alone, network accessible data storage device, such as a filer or NAS device, is capable of transferring data objects based on portions of the data objects. The device transfers portions of files, folders, and other data objects from a data store within the device to external secondary storage based on certain criteria, such as time-based criteria, age-based criteria, and so on. A portion may be one or more blocks of a data object, or one or more chunks of a data object, or other segments that combine to form or store a data object. For example, the device identifies one or more blocks of a data object that satisfy a certain criteria, and migrates the identified blocks to external storage, thereby freeing up storage space within the device. The device may determine that a certain number of blocks of a file have not been modified or called by a file system in a certain time period, and migrate these blocks to secondary storage.

Description

CROSS-REFERENCE TO RELATED APPLICATION
• This application claims priority to U.S. Patent Application No. 61/097,176 filed Sep. 15, 2008 (entitled DATA TRANSFER TECHNIQUES WITHIN DATA STORAGE DEVICES, SUCH AS NETWORK ATTACHED STORAGE PERFORMING DATA MIGRATION, Attorney Docket No. 60692-8066.US00), the entirety of which is incorporated by reference herein.
BACKGROUND
• Networked attached storage (NAS), often refers to a computing system, attached to a network, which provides file-based data storage services to other devices on the network. A NAS system, or NAS device, may include a file system (e.g., under Microsoft Windows) that manages the data storage services, but is generally controlled by other resources via an IP address or other communication protocol. A NAS device may also include an operating system, although the operating system is often configured only to facilitate operations performed by the NAS system. Mainly, a NAS device includes one or more redundantly arranged hard disks, such as RAID arrays. A NAS device works with various file-based and/or communication protocols, such as NFS (Network File System) for UNIX or LINUX systems, SMB/CIFS (Server Message Block/Common Internet File System) for Windows systems, or iSCSI (Internet SCSI) for IP communications.
• NAS devices provide a few similar functionalities to Storage Area Networks (SANs), although typical NAS devices only facilitate file level storage. Some hybrid systems exist, which provide both NAS and SAN functionalities. However, in these hybrid systems, such as Openfiler on LINUX, the NAS device serves the SAN device at the file level, and not at a file system level, such as at the individual file level. For example, the assignee's U.S. Pat. No. 7,546,324, entitled Systems and Methods for Performing Storage Operations Using Network Attached Storage, describes how individual files in a NAS device can be written to secondary storage, and are replaced in the NAS device with a stub having a pointer to the secondary storage location where the file now resides.
• A NAS device may provide centralized storage to client computers on a network, but may also assist in load balancing and fault tolerance for resources such as email and/or web server systems. Additionally, NAS devices are generally smaller and easy to install to a network.
• NAS device performance generally depends on traffic and the speed of the traffic on the attached network, as well as the capacity of a cache memory on the NAS device. Because a NAS device supports multiple protocols and contains reduced processing and operating systems, its performance may suffer when many users or many operations attempt to utilize the NAS device. The contained hardware intrinsically limits a typical NAS device, because it is self-contained and self-supported. For example, the capacity of its local memory may limit a typical NAS device's ability to provide data storage to a network, among other problems.
• The need exists for a system that overcomes the above problems, as well as one that provides additional benefits. Overall, the examples herein of some prior or related systems and their associated limitations are intended to be illustrative and not exclusive. Other limitations of existing or prior systems will become apparent to those of skill in the art upon reading the following Detailed Description.
BRIEF DESCRIPTION OF THE DRAWINGS
• FIG. 1 is a block diagram illustrating components of a data stream utilized by a suitable data storage system.
• FIG. 2 is a block diagram illustrating an example of a data storage system.
• FIG. 3 is a block diagram illustrating an example of components of a server used in data storage operations.
• FIG. 4 is a block diagram illustrating a NAS device within a networked computing system.
• FIG. 5 is a block diagram illustrating the components of a NAS device configured to perform data migration.
• FIGS. 6A and 6B are schematic diagrams illustrating a data store before and after a block-based data migration, respectively.
• FIG. 7 is a flow diagram illustrating a routine for performing block-level data migration in a NAS device.
• FIG. 8 is a flow diagram illustrating a routine for performing chunk-level data migration in a NAS device
• FIG. 9 is flow diagram illustrating a routine for block-based or chunk-based data restoration and modification via a NAS device.
DETAILED DESCRIPTIONOverview
• Described in detail herein is a system and method that transfers or migrates data objects within a stand-alone network storage device, such as a filer or network-attached storage (NAS) device. In some examples, a NAS device transfers segments, portions, increments, or proper subsets of data objects stored in local memory of the NAS device. The NAS device may transfer portions of files, folders, and other data objects from a cache to secondary storage based on certain criteria, such as time-based criteria, age-based criteria, and so on. A portion may be one or more blocks of a data object, or one or more chunks of a data object, or other data portions that combine to form, store, and/or contain a data object, such as a file.
• In some examples, the NAS device performs block-based migration of data. A data migration component within the NAS device identifies one or more blocks of a data object stored in a cache or data storage that satisfy a certain criteria, and migrates the identified blocks. For example, the data migration component may determine that a certain number of blocks of a file have not been modified or called by a file system within a certain time period, and migrate these blocks to secondary storage. The data migration component then maintains the other blocks of the file in primary storage. In some cases, the data migration component automatically migrates data without requiring user input. Additionally, the migration may be transparent to a user.
• In some examples, the NAS device performs chunk-based migration of data. A chunk is, for example, a group or set of blocks. One or more chunks may comprise a portion of a file, folder, or other data object. The data migration component identifies one or more chunks of a data object that satisfy a certain criteria, and migrates the identified chunks. For example, the data migration component may determine that a certain number of chunks of a file have not been modified or called by a file system in a certain time period, and migrate these chunks to secondary storage. The system then maintains the other chunks of the file in the cache or data storage of the NAS device.
• Network-attached storage, such as a filer or NAS device, and associated data migration components and processes, will now be described with respect to various examples. The following description provides specific details for a thorough understanding of, and enabling description for, these examples of the system. However, one skilled in the art will understand that the system may be practiced without these details. In other instances, well-known structures and functions have not been shown or described in detail to avoid unnecessarily obscuring the description of the examples of the system.
• The terminology used in the description presented below is intended to be interpreted in its broadest reasonable manner, even though it is being used in conjunction with a detailed description of certain specific examples of the system. Certain terms may even be emphasized below; however, any terminology intended to be interpreted in any restricted manner will be overtly and specifically defined as such in this Detailed Description section. A suitable data storage system will first be described, followed by a description of suitable stand-alone devices. Following that, various data migration and data recovery processes will be discussed.
Suitable System
• Referring toFIG. 1, a block diagram illustrating components of a data stream utilized by a suitable data storage system, such as a system that performs network attached storage, is shown. Thestream110 may include aclient111, amedia agent112, and asecondary storage device113. For example, in storage operations, the system may store, receive and/or prepare data, such as blocks or chunks, to be stored, copied or backed up at a server orclient111. The system may then transfer the data to be stored tomedia agent112, which may then refer to storage policies, schedule policies, and/retention policies (and other policies) to choose asecondary storage device113, such as a NAS device that receives data and transfers data to attached secondary storage devices. Themedia agent112 may include or be associated with a NAS device, to be discussed herein.
• Thesecondary storage device113 receives the data from themedia agent112 and stores the data as a secondary copy, such as a backup copy. Secondary storage devices may be magnetic tapes, optical disks, USB and other similar media, disk and tape drives, and so on. Of course, the system may employ other configurations of stream components not shown in the Figure.
• Referring toFIG. 2, a block diagram illustrating an example of adata storage system200 is shown. Data storage systems may contain some or all of the following components, depending on the needs of the system.FIG. 2 and the following discussion provide a brief, general description of a suitable computing environment in which the system can be implemented. Although not required, aspects of the system are described in the general context of computer-executable instructions, such as routines executed by a general-purpose computer, e.g., a server computer, wireless device or personal computer. Those skilled in the relevant art will appreciate that the system can be practiced with other communications, data processing, or computer system configurations, including: Internet appliances, network PCs, mini-computers, mainframe computers, and the like. Indeed, the terms “computer,” “host,” and “host computer” are generally used interchangeably herein, and refer to any of the above devices and systems, as well as any data processor.
• Aspects of the system can be embodied in a special purpose computer or data processor that is specifically programmed, configured, or constructed to perform one or more of the computer-executable instructions explained in detail herein. Aspects of the system can also be practiced in distributed computing environments where tasks or modules are performed by remote processing devices, which are linked through a communications network, such as a Local Area Network (LAN), Wide Area Network (WAN), Storage Area Network (SAN), Fibre Channel, or the Internet. In a distributed computing environment, program modules may be located in both local and remote memory storage devices.
• Aspects of the system may be stored or distributed on computer-readable media, including tangible storage media, such as magnetically or optically readable computer discs, hard-wired or preprogrammed chips (e.g., EEPROM semiconductor chips), nanotechnology memory, biological memory, or other data storage media. Alternatively, computer implemented instructions, data structures, screen displays, and other data under aspects of the system may be distributed over the Internet or over other networks (including wireless networks), on a propagated signal on a propagation medium (e.g., an electromagnetic wave(s), a sound wave, etc.) over a period of time, or they may be provided on any analog or digital network (packet switched, circuit switched, or other scheme). Those skilled in the relevant art will recognize that portions of the system reside on a server computer, while corresponding portions reside on a client computer, and thus, while certain hardware platforms are described herein, aspects of the system are equally applicable to nodes on a network.
• For example, thedata storage system200 contains astorage manager210, one ormore clients111, one ormore media agents112, and one ormore storage devices113.Storage manager210controls media agents112, which may be responsible for transferring data tostorage devices113.Storage manager210 includes ajobs agent211, amanagement agent212, adatabase213, and/or aninterface module214.Storage manager210 communicates with client(s)111. One ormore clients111 may access data to be stored by the system fromdatabase222 via adata agent221. The system usesmedia agents112, which containdatabases231, to transfer and store data intostorage devices113. Thestorage devices113 may include network attached storage, such as the NAS devices described herein.Client databases222 may contain data files and other information, while media agent databases may contain indices and other data structures that assist and implement the storage of data into secondary storage devices, for example.
• The data storage and recovery system may include software and/or hardware components and modules used in data storage operations. The components may be storage resources that function to copy data during storage operations. The components may perform other storage operations (or storage management operations) other that operations used in data stores. For example, some resources may create, store, retrieve, and/or migrate primary or secondary data copies of data. Additionally, some resources may create indices and other tables relied upon by the data storage system and other data recovery systems. The secondary copies may include snapshot copies and associated indices, but may also include other backup copies such as HSM copies, archive copies, auxiliary copies, and so on. The resources may also perform storage management functions that may communicate information to higher level components, such as global management resources.
• In some examples, the system performs storage operations based on storage policies, as mentioned above. For example, a storage policy includes a set of preferences or other criteria to be considered during storage operations. The storage policy may determine or define a storage location and/or set of preferences about how the system transfers data to the location and what processes the system performs on the data before, during, or after the data transfer. In some cases, a storage policy may define a logical bucket in which to transfer, store or copy data from a source to a data store, such as storage media. Storage policies may be stored instorage manager210, or may be stored in other resources, such as a global manager, a media agent, and so on. Further details regarding storage management and resources for storage management will now be discussed.
• Referring toFIG. 3, a block diagram illustrating an example of components of a server used in data storage operations is shown. A server, such asstorage manager210, may communicate withclients111 to determine data to be copied to storage media. As described above, thestorage manager210 may contain ajobs agent211, amanagement agent212, adatabase213, and/or an interface module.Jobs agent211 may manage and control the scheduling of jobs (such as copying data files) fromclients111 tomedia agents112.Management agent212 may control the overall functionality and processes of the data storage system, or may communicate with global managers.Database213 or another data structure may store storage policies, schedule policies, retention policies, or other information, such as historical storage statistics, storage trend statistics, and so on. Interface module215 may interact with a user interface, enabling the system to present information to administrators and receive feedback or other input from the administrators or with other components of the system (such as via APIs).
Suitable Storage Devices
• Referring toFIG. 4, a block diagram illustrating components of a networked data storage device, such as a filer orNAS device440, configured to perform data migration within a networked computing system is shown. (While the examples below discuss a NAS device, any architecture or networked data storage device employing the following principles may be used, including a proxy computer coupled to the NAS device). Thecomputing system400 includes adata storage system410, such as the tiereddata storage system200.Client computers420, includingcomputers422 and424, are associated with users that generate data to be stored in secondary storage. Theclient computers422 and424 communicate with thedata storage system410 over anetwork430, such as a private network such as an Intranet, a public network such as the Internet, and so on. Thenetworked computing system400 includes network attached storage, such asNAS device440. TheNAS device440 includes NAS-based storage or memory, such as acache444, for storing data received from the network, such as data fromclient computers422 and424. (The term “cache” is used generically herein for any type of storage, and thus thecache444 can include any type of storage for storing of data files within the NAS device, such as magnetic disk, optical disk, semiconductor memory, or other known types of storage such as magnetic tape or types of storage hereafter developed.) Thecache444 may include an index or other data structure in order to track where data is eventually stored or the index may be stored elsewhere, such as on the proxy computer. The index may include information associating the data with information identifying a secondary storage device that stored the data, or other information. For example, as described in detail below, the index may include both an indication of which blocks have been written to secondary storage (and where they are stored in secondary storage), and a look up table that maps blocks to individual files stored within the NAS andNAS device440.
• TheNAS device440 also includes adata migration component442 that performs data migration on data stored in thecache444. While shown inFIG. 4 as being within theNAS device440, thedata migration component442 may be on a proxy computer coupled to the NAS device. In some cases, thedata migration component442 is a device driver or agent that performs block-level data migration of data stored in the cache. In some cases, thedata migration component442 performs chunk-based data migration of data stored in the cache. Additionally, in some cases thedata migration component442 may perform file-based data migration, or a combination of two or more types of data migration, depending on the needs of the system. During data migration, the NAS device transfers data from the cache of the device to one or moresecondary storage devices450 located on thenetwork430, such asmagnetic tapes452,optical disks454, or othersecondary storage456. The NAS device may include various data storage components when identifying and transferring data from thecache444 to thesecondary storage devices450. These components will now be discussed.
• Referring toFIG. 5, a block diagram illustrating the components of aNAS device440 configured to perform data migration is shown. In addition to adata migration component442 andcache444, theNAS device440 may include aninput component510, adata reception component520, afile system530, and anoperating system540. Theinput component510 may receive various inputs, such as via an iSCSI protocol. That is, the NAS device may receive commands or control data from adata storage system410 over IP channels. For example, thedata storage system410 may send commands to a NAS device's IP address in order to provide instructions to the NAS device. Thedata reception component520 may receive data to be stored over multiple protocols, such as NFS, CIFS, and so on. For example, a UNIX based system may send data to be stored to the NAS device over a NFS communication channel, while a Windows based system may send data to be stored to the NAS device over a CIFS communication channel.
• Additionally, theNAS device440 may include a number of data storage resources, such as adata storage engine560 to direct reads from writes to thedata store444, and one ormore media agents570. Themedia agents570 may be similar to themedia agents112 described herein. In some cases, theNAS device440 may include two ormore media agents570, such asmultiple media agents570 externally attached to theNAS device440. TheNAS device440 may expand its data storage capabilities by addingmedia agents570, as well as other components.
• As discussed herein, theNAS device440 includes a data migration component capable of transferring some or all of the data stored in thecache442. In some examples, thedata migration component442 requests and/or receives information from acallback layer550, or other intermediate component, within theNAS device440. Briefly, thecallback layer550 intercepts calls for data between thefile system530 and thecache444, and tracks these calls to provide information to thedata migration component442 regarding when data is changed, updated, and/or accessed by thefile system530. Further details regarding thecallback layer550 and other intermediate components will now discussed.
• In some examples, the NAS device monitors the transfer of data from thefile system530 to thecache444 via thecallback layer550. Thecallback layer550 not only facilitates the migration of data portions from data storage on the NAS device to secondary storage, but also facilitates read back or callback of that data from the secondary storage back to the NAS device. While described at times herein as a device driver or agent, thecallback layer550 may be a layer, or additional file system, that resides on top of thefile system530. Thecallback layer550 may intercept data requests from thefile system530, in order to identify, track and/or monitor data requested by thefile system530 and store information associated with these requests in a data structure, such as a bitmap similar to the one shown in Table 1. Thus, the callback layer stores information identifying when a data portion is accessed by tracking calls from thefile system530 to thecache530. For example, Table 1 provides entry information that tracks calls to a data store:

• TABLE 1
  Chunk of File1	Access Time
  File1.1	09.05.2008 @12:00
  File1.2	09.05.2008 @12:30
  File1.3	09.05.2008 @13:30
  File1.4	06.04.2008 @12:30

• In this example, thefile system530 creates a data object named “File1,” using a chunking component (described herein) to divide the file into four chunks: “File1.1,” “File1.2,” “File1.3,” and “File1.4.” Thefile system530 stores the four chunks to thecache444 on Jun. 4, 2008. According to the table, the file system can determine that it has not accessed chunk File1.4 since its creation, and most recently accessed the other chunks on Sep. 5, 2008. Of course, Table 1 may include additional, other or different information, such as information identifying a location of the chunks, information identifying the type of media storing the chunks, information identifying the blocks within the chunk, and/or other information or metadata.
• Thus, providing data migration to the NAS device enables the device to facilitate inexpensive, transparent storage to a networked computing system, to free up storage space by migrating or archiving stale data to other locations, among other benefits. Of course, non-networked computing systems may also store data to the NAS devices described herein. Because the NAS devices described herein can be easily and quickly installed on networks, they provide users, such as network administrators, with a quick and efficient way to expand their storage capacity without incurring the typical costs associated with typical NAS devices that do not perform data migration.
• For example, adding a NAS device described herein to an existing networked computing system can provide the computing system with expanded storage capabilities, but can also provide the computing system with other data storage functionality. In some examples, the NAS device described herein includes a data storage engine (e.g., a common technology engine, or CTE, provided by Commvault Systems, Inc. of Oceanport, N.J.), the NAS device may act as a backup server. For example, such a device may perform various data storage functions normally provided by a backup server, such as single instancing, data classification, mirroring, content indexing, data backup, encryption, compression, and so on. Thus, in some examples, the NAS device described herein acts as a fully functional and independent device an administrator can attach to a network to perform virtually any data storage function.
• Also, in some cases, the NAS device described herein may act to perform fault tolerance in a data storage system. For example, the clustering of NAS devices on a system may provide a higher level of security, because processes on one device can be replicated on another. Thus, attaching two or more of the NAS devices described herein may provide an administrator with the redundancy or security required in some data storage systems.
Data Migration in Storage Devices
• As described herein, in some examples, the NAS device leverages block-level or chunk-based data migration in order to provide expanded storage capabilities to a networked computing system.
• Block-level migration, or block-based data migration, involves migrating disk blocks from the data store orcache444 to secondary media, such asstorage devices550. Using block-level migration, theNAS device440 transfers blocks from the cache that have not been recently accessed to secondary storage, freeing up space on the cache.
• As described above, the system can transfer or migrate certain blocks of a data object from one data store to another, such as from a cache in a NAS device to secondary storage. Referring toFIGS. 6A-6B, a schematic diagram illustrating contents of two data stores before and after a block-based data migration is shown. InFIG. 6A, afirst data store610 contains primary copies (i.e., production copies) of two data objects, afirst data object620 and asecond data object630. The first data object comprises blocks A and A¹, where blocks A are blocks that satisfy or meet certain storage criteria (such as blocks that have not been modified since creation or not been modified within a certain period of time) and blocks A′ are blocks that do not meet the criteria (such as blocks that have been modified within the certain time period). The second data object comprises blocks B and B′, where blocks B satisfy the criteria and blocks B′ do not meet the criteria.
• FIG. 6B depicts thefirst data store610 after a block-based data migration of the twodata objects620 and630. In this example, the system only transfers the data from blocks that satisfy a criteria (blocks A and B) from thefirst data store610 to asecond data store640, such assecondary storage642,644. The secondary storage may include one or more magnetic tapes, one or more optical disks, and so on. The system maintains data in the remaining blocks (blocks A′ and B′) within thefirst data store610.
• The system can perform file system data migration at a block level, unlike previous systems that only migrate data at the file level (that is, they have a file-level granularity). By tracking migrated blocks, the system can also restore data at the block level, which may avoid cost and time problems associated with restoring data at the file level.
• Referring toFIG. 7, a flow diagram illustrating a routine700 for performing block-level data migration in a NAS device is shown. Instep710, the NAS device, via thedata migration component442, identifies data blocks within a cache that satisfy a certain criteria. Thedata migration component442 may compare some or all of the blocks (or, information associated with the blocks) in the cache with predetermined criteria. The predetermined criteria may be time-based criteria within a storage policy or data retention policy.
• In some examples, thedata migration component442 identifies blocks set to be “aged off” from the cache. That is, thedata migration component442 identifies blocks created, changed, or last modified before a certain date and time. For example, the system may review a cache for all data blocks that satisfy a criterion or criteria. The data store may be an electronic mailbox or personal folders (.pst) file for a Microsoft Exchange user, and the criterion may define, for example, all blocks or emails last modified or changed thirty days ago or earlier. Thecomponent442 compares information associated with the blocks, such as metadata associated with the blocks, to the criteria, and identifies all blocks that satisfy the criteria. For example, thecomponent442 identifies all blocks in the .pst file not modified within the past thirty days. The identified blocks may include all the blocks for some emails and/or a portion of the blocks for other emails. That is, for a given email (or data object), a first portion of the blocks that include the email may satisfy the criteria, while a second portion of the blocks that include the same email may not satisfy the criteria. In other words, a file or a data object can be divided into parts or portions, and only some of the parts or portions change.
• To determine which blocks have changed, and when, the NAS device can monitor the activity of a NAS device'sfile system530 via thecallback layer550. The NAS device may store a data structure, such as a bitmap, table, log, and so on within thecache444 or other memory in the NAS device or elsewhere, and update the data structure whenever the file system calls thecache444 to access and update or change data blocks within thecache444. Thecallback layer550 traps commands to thecache444, where that command identifies certain blocks on a disk for access or modifications, and writes to the data structure the changed blocks and the time of the change. The data structure may include information such as an identification of changed blocks and a date and a time the blocks were changed. The data structure, which may be a table, bitmap, or group of pointers, such as a snapshot, may also include other information, such as information that maps file names to blocks, information that maps chunks to blocks and/or file names, and so on, and identify when accesses/changes were made. Table 2 provides entry information for tracking the activity of a file system with the “/users” directory:

• 	TABLE 2
  	Blocks	Date and Time Modified
  	/users/blocks1-100	09.08.2008 @14:30
  	/users/blocks101-105	09.04.2008 @12:23
  	/users2/blocks106-110	09.04.2008 @11:34
  	/users3/blocks110-1000	08.05.2008 @10:34

• Thus, if a storage policy identified the time Aug. 30, 2008 @12:00 as a threshold time criteria, where data modified after the time is to be retained, the system would identify, instep710, blocks110-1000 as having satisfied the criteria. Thus, the system, via theintermediate component420, can monitor what blocks are requested by a file system, and act accordingly, as described herein.
• Instep720, the NAS device transfers data within the identified blocks from the cache to amedia agent570, to be stored in a different data store. The system may perform some or all of the processes described with respect toFIGS. 1-3 when transferring the data to the media agent. For example, before transferring data, the system may review a storage policy as described herein to select a media agent, such asmedia agent112, based on instructions within the storage policy. Instep725, the system optionally updates an allocation table, such as a file allocation table (FAT) for thefile system530 associated with the NAS device, to indicate the data blocks that no longer contain data and are now free to receive and store data from the file system.
• Instep730, via themedia agent570, theNAS device440 stores data from the blocks to a different data store. In some cases, the NAS device, via themedia agent570, stores the data from the blocks to a secondary storage device, such as amagnetic tape452 oroptical disk454. For example, the NAS device may store the data from the blocks in secondary copies of the data store, such as a backup copy, an archive copy, and so on.
• The NAS device may create, generate, update, and/or include an allocation table, (such as a table for the data store) that tracks the transferred data and the data that was not transferred. The table may include information identifying the original data blocks for the data, the name of the data object (e.g., file name), the location of any transferred data blocks (including, e.g., offset information), and so on. For example, Table 3 provides entry information for an example .pst file:

• 	TABLE 3
  	Name of Data Object	Location of data
  	Email1	C:/users/blocks1-100
  	Email2.1 (body of email)	C:/users/blocks101-120
  	Email2.2 (attachment)	X:/remov1/blocks1-250
  	Email3	X:/remov2/blocks300-500

• In the above example, the data for “Email2” is stored in two locations, the cache (C:/) and an off-site data store (X:/). The system maintains the body of the email, recently modified or accessed, at a location within a data store associated with a file system, “C:/users/blocks101-120.” The system stores the attachment, not recently modified or accessed, in a separate data store, “X:/remov1/blocks1-250.” Of course, the table may include other information, fields, or entries not shown. For example, when the system stored data to tape, the table may include tape identification information, tape offset information, and so on.
• Chunked file migration, or chunk-based data migration, involves splitting a data object into two or more portions of the data object, creating an index that tracks the portions, and storing the data object to secondary storage via the two or more portions. Among other things, the chunk-based migration provides for fast and efficient storage of a data object. Additionally, chunk-based migration facilitates fast and efficient recall of a data object, such as the large files described herein. For example, if a user modifies a migrated file, chunk-based migration enables a data restore component to only retrieve and migrate back to secondary storage the chunk containing the modified portion of the file, and not the entire file.
• As described above, in some examples the NAS device migrates chunks of data (sets of blocks) that comprise a data object from thecache444 to another. A data object, such as a file, may comprise two or more chunks. A chunk may be a logical division of a data object. For example, a .pst file may include two or more chucks: a first chunk that stores associated with an index of a user's mailbox, and one or more chunks that stores email, attachments, and so on within the user's mailbox. A chunk is a proper subset of all the blocks that contain a file. That is, for a file contained or defined by n blocks, the largest chunk of the file contains at most n-1 blocks.
• In some cases, thedata migration component442 may include a chunking component that divides data objects into chunks. The chunking component may receive files to be stored in thecache444, divide the files into two or more chunks, and store the files as two or more chunks in the cache. The chunking component may update an index that associated information associated with files with the chunks of the file, the data blocks of the chunks, and so on.
• The chunking component may perform different processes when determining how to divide a data object. For example, the chunking component may include indexing, header, and other identifying information or metadata in a first chunk, and include the payload in other chunks. The chunking component may identify and/or retrieve file format or schema information from an index, FAT, NFS, or other allocation table in the file system to determine where certain chunks of a data object reside (such as the first or last chunk of a large file). The chunking component may follow a rules-based process when dividing a data object. The rules may define a minimum or maximum data size for a chunk, a time of creation for data within a chunk, a type of data within a chunk, and so on.
• For example, the chunking component may divide a user mailbox (such as a .pst file) into a number of chunks, based on various rules that assign emails within the mailbox to chunks based on the metadata associated with the emails. The chunking component may place an index of the mailbox in a first chunk and the emails in other chunks. The chunking component may then divide the other chunks based on dates of creation, deletion or reception of the emails, size of the emails, sender of the emails, type of emails, and so on. Thus, as an example, the chunking component may divide a mailbox as follows:

• 	User1/Chunk1	Index
  	User1/Chunk2	Sent emails
  	User1/Chunk3	Received emails
  	User1/Chunk4	Deleted emails
  	User1/Chunk5	All Attachments.

  
  Of course, other divisions are possible. Chunks may not necessarily fall within logical divisions. For example, the chunking component may divide a data object based on information or instructions not associated with the data object, such as information about data storage resources, information about a target secondary storage device, historical information about previous divisions, and so on.
• Referring toFIG. 8, a flow diagram illustrating a routine800 for performing chunk-level data migration in a NAS device is shown. Instep810, the system identifies chunks of data blocks within a data store that satisfy one or more criteria. The data store may store large files (>50 MB), such as databases associated with a file system, SQL databases, Microsoft Exchange mailboxes, virtual machine files, and so on. The system may compare some or all of the chunks (or, information associated with the chunks) of the data store with predetermined and/or dynamic criteria. The predetermined criteria may be time-based criteria within a storage policy or data retention policy. The system may review an index with the chunking component815 when comparing the chunks with applicable criteria.
• Instep820, the NAS device transfers data within the identified chunks from the data store to a media agent, to be stored in a different data store. The NAS device may perform some or all of the processes described with respect toFIGS. 1-3 when transferring the data to the media agent. For example, the NAS device may review a storage policy assigned to the data store and select a media agent based on instructions within the storage policy. Instep825, the system optionally updates an allocation table, such as a file allocation table (FAT) for a file system associated with the NAS device, to indicate the data blocks that no longer contain data and are now free to receive and store data from the file system.
• Instep930, via one ormore media agents570, theNAS device440 stores the data from the chunks to a different data store. In some cases, the system, via the media agent, stores the data to a secondary storage device, such as a magnetic tape or optical disk. For example, the system may store the data in secondary copies of the data store, such as a backup copy, and archive copy, and so on.
Data Recovery in Storage Devices
• A data storage system, using a NAS device leveraging the block-based or chunk-based data migration processes described herein, is able to restore portions of files instead of entire files, such as individual blocks or chunks that comprise portions of the files. Referring toFIG. 9, a flow diagram illustrating a routine900 for block-based or chunk-based data restoration and modification is shown. Instep910, the system, via a restore or data recovery component, receives a request to modify a file located in a cache of a NAS device or in secondary storage in communication with a NAS device. For example, a user submits a request to a file system to provide an old copy of a large PowerPoint presentation so the user can modify a picture located on slide 5 of 300 of the presentation.
• Instep920, the system identifies one or more blocks or one or more chunks associated with the request. For example, thecallback layer550 of the system looks to a table similar to Table 3, identifies blocks associated with page 5 of the presentation and blocks associated with a table of contents of the presentation, and contacts a NAS device that stored or migrated the blocks on secondary storage.
• Instep930, the system, via the NAS device, retrieves the identified blocks or chunks from the secondary storage and presents them to the user. For example, the system only retrieves page 5 and table of contents of the presentation and presents the pages to the user.
• Instep940, the system receives input from a user to modify the retrieved blocks or chunks. For example, the user updates the PowerPoint presentation to include a different picture. Instep950, the system transfers data associated with the modified blocks or chunks back to the NAS device, where it remains in a cache or is transferred to secondary storage. For example, the system transfers the modified page 5 to the data store. The system may also update a table that tracks access to the data store, such as Table 1 or Table 3.
• Thus, the system, leveraging block-based or chunk-based data migration in a NAS device, restores only portions of data objects required by a file system. Such restoration can be, among other benefits, advantageous over systems that perform file-based restoration, because those systems restore entire files, which can be expensive, time consuming, and so on. Some files, such as .pst files, may contain large amounts of data. File-based restoration can therefore be inconvenient and cumbersome, among other things, especially when a user only requires a small portion of a large file.
• For example, a user submits a request to the system to retrieve an old email stored in a secondary copy on removable media via a NAS device. The system identifies a portion of a .pst file associated with the user that contains a list of old emails in the cache of the NAS device, and retrieves the list. That is, the system has knowledge of the chunk that includes the list (e.g., a chunking component may always include the list in a first chunk of a data object), accesses the chunk, and retrieves the list. The other portions (e.g., all the emails with the .pst file), were transferred from the NAS device secondary storage. The user selects the desired email from the list. The NAS device, via an index in the cache that associates chunks with data or files (such as an index similar to Table 3), identifies the chunk that contains the email, and retrieves the chunk from associate secondary storage for presentation to the user. Thus, the NAS device is able to restore the email without restoring the entire mailbox (.pst file) associated with the user.
• As noted above, thecallback layer550 maintains a data structure that not only tracks where a block or chunk resides on secondary storage, but also which file was affected based on the migration of that block or chunk. Portions of large files may be written to secondary storage to free up space in thedata store444 of theNAS device440. Thus, to the network, the total data storage of the NAS device is much greater than that actually available within thedata store444. For example, while thedata store444 may have only a 100 gigabyte capacity, its capacity may actually appear as 300 gigabytes, with over 200 gigabytes migrated to secondary storage.
• To help ensure sufficient space to write back data from secondary storage to thedata store444 of theNAS device440, the data store may be partitioned to provide a callback or read-back cache. For example, a disk cache may be established in thedata store444 of theNAS device440 for the NAS device to write back data read from secondary storage. The amount of the partition is configurable, and may be, for example, between 5 and 20 percent of the total capacity of thedata store440. In the above example, with a 100gigabyte data store444, 10 gigabytes may be reserved (10 percent) for data called back from secondary storage to theNAS device440. This disk partition or callback cache can be managed in known ways, such that data called back to this disk partition can have the oldest data overwritten when room is needed to write new data.
Conclusion
• From the foregoing, it will be appreciated that specific examples of the data recovery system have been described herein for purposes of illustration, but that various modifications may be made without deviating from the spirit and scope of the system. For example, although files have been described, other types of content such as user settings, application data, emails, and other data objects can be imaged by snapshots. Accordingly, the system is not limited except as by the appended claims.
• Unless the context clearly requires otherwise, throughout the description and the claims, the words “comprise,” “comprising,” and the like are to be construed in an inclusive sense, as opposed to an exclusive or exhaustive sense; that is to say, in the sense of “including, but not limited to.” The word “coupled”, as generally used herein, refers to two or more elements that may be either directly connected, or connected by way of one or more intermediate elements. Additionally, the words “herein,” “above,” “below,” and words of similar import, when used in this application, shall refer to this application as a whole and not to any particular portions of this application. Where the context permits, words in the above Detailed Description using the singular or plural number may also include the plural or singular number respectively. The word “or” in reference to a list of two or more items, that word covers all of the following interpretations of the word: any of the items in the list, all of the items in the list, and any combination of the items in the list.
• The above detailed description of embodiments of the system is not intended to be exhaustive or to limit the system to the precise form disclosed above. While specific embodiments of, and examples for, the system are described above for illustrative purposes, various equivalent modifications are possible within the scope of the system, as those skilled in the relevant art will recognize. For example, while processes or blocks are presented in a given order, alternative embodiments may perform routines having steps, or employ systems having blocks, in a different order, and some processes or blocks may be deleted, moved, added, subdivided, combined, and/or modified. Each of these processes or blocks may be implemented in a variety of different ways. Also, while processes or blocks are at times shown as being performed in series, these processes or blocks may instead be performed in parallel, or may be performed at different times.
• The teachings of the system provided herein can be applied to other systems, not necessarily the system described above. The elements and acts of the various embodiments described above can be combined to provide further embodiments.
• These and other changes can be made to the system in light of the above Detailed Description. While the above description details certain embodiments of the system and describes the best mode contemplated, no matter how detailed the above appears in text, the system can be practiced in many ways. Details of the system may vary considerably in implementation details, while still being encompassed by the system disclosed herein. As noted above, particular terminology used when describing certain features or aspects of the system should not be taken to imply that the terminology is being redefined herein to be restricted to any specific characteristics, features, or aspects of the system with which that terminology is associated. In general, the terms used in the following claims should not be construed to limit the system to the specific embodiments disclosed in the specification, unless the above Detailed Description section explicitly defines such terms. Accordingly, the actual scope of the system encompasses not only the disclosed embodiments, but also all equivalent ways of practicing or implementing the system under the claims.
• While certain aspects of the system are presented below in certain claim forms, the applicant contemplates the various aspects of the system in any number of claim forms. For example, while only one aspect of the system is recited as a means-plus-function claim under 35 U.S.C sec. 112, sixth paragraph, other aspects may likewise be embodied as a means-plus-function claim, or in other forms, such as being embodied in a computer-readable medium. (Any claims intended to be treated under 35 U.S.C. §112, ¶6 will begin with the words “means for”.) Accordingly, the applicant reserves the right to add additional claims after filing the application to pursue such additional claim forms for other aspects of the system.

Claims (22)

1. A network attached storage (NAS) device, wherein the network attached storage device is configured to be connected to a networked computing system, the networked computing system including one or more secondary data storage devices and one or more client computers connected via a network, the network attached storage device comprising:

a housing containing one or more components, the components including:

a data reception component, wherein the data reception component is configured to receive for storage multiple data files from the one or more client computers via the network;

an operating system, wherein the operating system is configured to provide a computing environment for the network attached storage device;

at least one processor, wherein the at least one processor is programmed to perform one or more data storage functions for the network attached storage device;

a non-volatile data store, wherein the non-volatile data store is configured to store the data files received from the data reception component;

a file system, wherein the file system is configured to manage, for the network attached storage device, the writing of data files to, and the reading of data files from, the non-volatile data store;

one or more media agents, wherein the one or more media agents are configured to receive instructions from the at least one processor and to transfer data stored in the non-volatile data store to the one or more secondary data storage devices, wherein the one or more secondary data storage devices are external to the network attached storage device but are accessible by the one or more media agents via the network; and

a data migration component, wherein the data migration component is configured to identify portions of at least some of the data files within the non-volatile data store and to migrate the identified data file portions from the network attached storage device,

wherein the identified data file portions are for storage by the one or more media agents to at least one of the one or more secondary storage devices,

wherein the data migration component is further configured to identify portions of a selected data file within the non-volatile data store based at least in part on a data storage criteria,

wherein the data storage criteria is associated with the writing of data to, and the reading of data from, portions of the selected data file by the file system,

wherein the identified portions of the selected data file are less than all of the selected data file, and

wherein the data migration component maintains a data structure that

tracks a logical location of the identified data file portions stored in the one or more secondary storage devices, and

maps the identified data file portions to the selected data file.

2. The network attached storage device ofclaim 1, further comprising:

a data interception component, wherein the data interception component is configured to intercept data transferred from the data reception component to the non-volatile data store and to update an index associating information identifying the transferred data with information identifying a time of transfer to the non-volatile data store.

3. The network attached storage device ofclaim 1, further comprising:

a data interception component, wherein the data interception component is configured to intercept access requests from the file system to the non-volatile data store and to update an index associating information identifying the access requests with information identifying a time of the access requests.

4. The network attached storage device ofclaim 1, wherein the data files consist of multiple blocks and wherein the data migration component identifies at least one block for migration from the network attached storage device, but not all of the multiple blocks, wherein the one block has an oldest access time as compared to other of the multiple blocks.

5. The network attached storage device ofclaim 1, wherein the data migration component is configured to identify data blocks in the non-volatile data store that have not been accessed by the file system within a predetermined time period or that have not changed since a predetermined time.

6. The network attached storage device ofclaim 1 wherein the non-volatile data store further comprising a reserved read-back cache, and wherein the network attached storage device further comprises a callback component configured to read back the identified data file portions stored in the one or more secondary storage devices and to write the identified data file portions to the read-back cache.

7. A computer-implemented method for tracking at least a first portion of at least one data object within a network attached storage (NAS) device coupled to a network, wherein the NAS device includes a NAS file system and a non-volatile data store, the method comprising:

accessing calls to or from the NAS file system for reading of data from or writing of data to the non-volatile data store of the NAS device,

wherein the at least one data object consists of multiple data blocks,

wherein the non-volatile data store of the NAS device stores the multiple data blocks of the at least one data object;

wherein the NAS file system of the NAS device controls the reading of data from or the writing of data to the multiple data blocks of the at least one data object, and

wherein the accessing includes identifying individual blocks or groups of blocks within the multiple data blocks of the at least one data object that the NAS file system of the NAS device reads data from or writes data to;

based on the accessing, identifying a portion of the multiple data blocks of the at least one data object that satisfies a data storage criteria,

wherein the data storage criteria is a time-based criteria; and,

based on the identifying, and independently of the NAS file system of the NAS device, updating a data structure, wherein the data structure—tracks the portion of the multiple data blocks, and

provides an indication of the at least one data object to which the portion of the multiple data blocks belongs.

8. The method ofclaim 7, further comprising:

transferring data stored in the portion of the multiple data blocks to a separate storage device, wherein the separate storage device is not contained by or within the NAS device but communicates with the NAS device over the network, wherein the network is a private network;

updating the data structure to include information associating the portion of the multiple data blocks with the separate storage device, wherein the data structure is an index is stored in the non-volatile data store of the NAS device; and

removing information from an allocation table associated with the NAS file system of the NAS device, and

wherein the at least one data object is a file, and wherein the portion of the multiple data blocks is less than all of the multiple data blocks for the file.

9. The method ofclaim 7, further comprising:

transferring data stored in the portion of the multiple data blocks to a separate storage device, wherein the separate storage device is not contained by or within the NAS device but communicates with the NAS device over the network; and,

updating the data structure to track a location of the portion of the multiple data blocks as being located in the separate storage device.

10. The method ofclaim 7, wherein the data storage criteria comprises a time period in which to retain data in a cache of the NAS device, or a time period in which a recent access of the portion must occur of the multiple data blocks.

11. A stand-alone data storage device, coupled to one or more external computing devices over a network, wherein at least one external storage device is also connected to the data storage device via the network, the data storage device comprising:

at least one processor;

a communication component coupled to the at least one processor and associated with a network address for the data storage device,

wherein the communication component receives data transfer commands from the one or more external computing devices on the network,

wherein the one or more external computing devices direct the data transfer commands to the data storage device via the network address for the data storage device, and

wherein the data transfer commands direct operation of the data storage device;

a non-volatile, internal data store, coupled to the at least one processor, wherein the internal data store stores data objects, wherein at least some of the data objects are comprised of multiple data blocks;

a data storage component that comprises program code, which when executed by the processor, performs data storage tasks with respect to the internal data store;

a file system that comprises program code, which when executed by the processor, stores and organizes data objects stored in the internal data store;

a call intercept layer, in communication with the file system, that comprises program code, which when executed by the processor, recognizes calls to or from the file system for reading of data from or writing of data to individual data blocks or groups of data blocks stored within the internal data store;

a data block identification component, in communication with the call intercept layer, that comprises program code, which when executed by the processor, identifies data blocks of the data object that satisfy a criteria, wherein the criteria is associated with the recognized calls to or from the file system for the reading of data from or the writing of data to the individual data blocks or groups of data blocks; and

an index component that comprises program code, which when executed by the processor, updates an index to include information associating the identified data blocks with information identifying the data object.

12. The data storage device ofclaim 11 wherein at least one data object is a file having n number of data blocks, and wherein the data storage device further comprises:

a media agent, in communication with the data block identification component, that comprises program code, which when executed by the processor, copies or transfers, via the network and to the external storage device, data for no more than n-1 identified data blocks; and

wherein the index component includes a bitmap or a data location table mapping the no more than n-1 identified data blocks to a logical location on the network.

13. The data storage device ofclaim 11 wherein at least one data object is a file having n number of data blocks, and wherein the data storage device further comprises:

a media agent, in communication with the data block identification component, that comprises program code, which when executed by the processor, copies or transfers, via the network and to the external storage device, data for no more than n-1 identified data blocks; and

wherein the index component updates the index to include information associating the transferred data with information identifying tape offsets for the secondary storage device that contains the transferred data.

14. The data storage device ofclaim 11, wherein the criteria defines a time period related to when the file system last read data from or wrote data to individual data blocks or groups of data blocks.

15. The data storage device ofclaim 11, wherein the criteria defines a time period in which changes were made to data contained by blocks of the data object.

16. A method performed by a network attached storage device for storing a portion of a data object in a secondary storage device associated with the network attached storage device, the method comprising:

identifying, within a cache of the network attached storage device, a data object having at least a first portion, wherein the first portion was last accessed by a file system of the network attached storage device before a predetermined time,

wherein a second portion of the data object was last accessed by the file system after the predetermined time;

transferring the first portion of the data object out of the network attached storage and to a secondary storage device communicatively coupled with the network attached storage device,

wherein the secondary storage device is external to the network attached storage device; and

maintaining the second portion of the data object in the cache of the network attached storage device.

17. A network attached storage device, comprising:

a cache, wherein the cache stores one or more data objects;

a media agent, wherein the media agent is configured to transfer portions of the one or more data objects from the cache to associated secondary storage devices, wherein the secondary storage devices are located external to the network attached storage device and configured to provide long term storage of data; and

a data identification component, wherein the data identification component is configured to identify to the media agent the portions of the data objects to be transferred to the secondary storage devices based on one or more storage criteria.

18. The network attached storage device ofclaim 17, further comprising:

an intermediate component, wherein the intermediate component tracks in an index all accesses of the one or more data objects by a file system within the network attached storage device, and wherein the data identification component identifies the portions of the data objects based on information within the index.

19. The network attached storage device ofclaim 17, wherein the identified portions are proper subsets of data blocks of the data objects.

20. The network attached storage device ofclaim 17, wherein the identified portions include chunks of the data objects created from a rule-based process of dividing the data object into two or more portions.

21. A system for storing a portion of a data object in a secondary storage device associated with a network attached storage (NAS) device, the system comprising:

at least one processor;

a data store;

callback layer and block identifying means for identifying, from calls to or from a file system within the NAS device, a first portion a data object within the data store of the NAS device, wherein the first portion was last accessed by the file system of the network attached storage device before a predetermined time, wherein a second portion of the data object was last accessed by the file system after the predetermined time;

media agent means for transferring the first portion of the data object to a secondary storage device associated with the network attached storage device; and

index means for tracking the second portion of the data object in the data store of the network attached storage device.

22. The system ofclaim 21, further comprising a read-back cache, formed from the data store, and wherein the callback layer and block identifying means is further configured for reading back the first portion of the data object stored to the secondary storage device and for writing the first portion to the read-back cache.

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