An instant snapshot is an in-place backup of a diskthat can be used to rapidly create a new disk in minutes.

Instant snapshots capture data at a specific point in time. They are optimizedfor rapidly restoring captured data to a new disk. Use instant snapshots toquickly recover data in cases where the zone and disk are still intact but thedata on the disk has been lost or corrupted, such as the following:

• User error
• Failed software upgrades
• Application-level failures

Creating an instant snapshot of a disk before one of these events occurs letsyou quickly restore the data from the instant snapshot to a new disk. Reducingthe time to restore a disk helps avoid downtime and long maintenance windows.

Instant snapshots are incremental and can be more cost effective than usingmultiple disk clones.

Warning: Instant snapshots of a disk are deleted when the disk is deleted anddon't protect against zonal or regional failures. To protect your data fromzonal or regional failures, create a backup in another region usingstandard snapshotsor anotherdata backup option.

Snapshot types

You can back up a disk with snapshots.The three types of snapshots—standard, instant, and archive—allcapture the contents of a disk at a specific point in time.

The following are the key differences between the snapshot types:

• Retention after source disk deletion
• Data recovery time (RTO)
• Storage location

Retention after source disk deletion

An instant snapshot of a diskonly exists until the source disk is deleted.Standard and archive snapshots aren't deleted with the source disk. Therefore,if you want to retain a backup of a disk after you delete the disk itself, usearchive or standard snapshots.

Data recovery time

The data recovery time is the length of time needed tocreate a new disk from a snapshot and varies by snapshot type.

• Instant snapshots offer the lowest and best recovery times.
• Standard snapshots have faster data recovery times than archive snapshots.
• Archive snapshots have the longest data recovery times, but offer the most cost efficient storage.

Storage location by snapshot type

The storage location is the zone or region where Compute Engine storesthe snapshot.

• Instant snapshots are local disk backups that are stored in the same zone or regionas the source disk.
• Archive and standard snapshots are remote backups of disk data storedseparately from the source disk.

Compute Engine stores archive and standard snapshots in the same manner. Copies of archive and standard snapshots are stored acrossmultiple locations with automatic checksums to ensure the integrity of yourdata.

Unless otherwise specified, references to standard snapshots include archive snapshots.

Snapshot type comparison

The following table compares the differences between the types of snapshots:

Snapshot type	Best for	Storage redundancy	Support for Hyperdisk	Can be created with snapshot schedules	Deleted on source disk deletion
Standard snapshots	Geo-redundant data backup to safeguard against local, zonal, and regional outages.	Redundant. Stored in one or more regions. Not restricted to the same zone or region as the source disk.	Yes	Yes	No
Archive snapshots	Same as standard snapshots, but for data that is rarely accessed and must be retained for several months or years. Lower cost geo-redundant storage that is better suited for data related to compliance, audits, and cold-storage.	Redundant. Stored in one or more regions. Not restricted to the same zone or region as the source disk.	Yes	No	No
Instant snapshots	In-place data backup to enable quick restore to a new disk in case of user error or application corruption.	Not redundant. Stored in the same zone or region as source disk only.	Yes, for certain Hyperdisk types*	No	Yes

^*You can't create instant snapshots of Hyperdisk ML or Hyperdisk Throughput volumes.

In addition to snapshots, Compute Engine offers other data backup options.Review the chart describingdata backup options.

The information in this document applies to instant snapshots. Learn moreabout standard snapshots.

Supported disk types

Instant snapshots support the following disk types:

• Hyperdisk Balanced
• Hyperdisk Balanced High Availability
• Hyperdisk Extreme
• Persistent Disk, including Extreme Persistent Disk

You can back up both boot and non-boot disks with instant snapshots.

Instant snapshots can be used with zonal and regional disks. You can't use instant snapshotsto back up Hyperdisk Throughput or Hyperdisk ML volumes.

An instant snapshot of a disk is always stored in the same zone or region as the disk.For example, instant snapshots of a disk in theus-east1-d zone arestored in theus-east1-d zone. Likewise, instant snapshots of a regionalPersistent Disk volume in theus-east1 region are stored in theus-east1 region.

Access the data on a snapshot

The data in snapshots is read-only.To access or modify the data on a snapshot,create a disk from the snapshot.

Create adisk cloneif you want a writeable, immediately accessible copy of a disk for debuggingor experimentation.

Work with instant snapshots

• Create instant snapshots of individual disksorgroups of disks(Preview).

• To verify, view, or modify the data on a snapshot,create a disk from the snapshot.After you create the disk,you can attach it to a VM or create a new VM from the disk, if it is a boot disk.

• If you no longer need an instant snapshot,delete the snapshotto reduce your storage costs.

• You canlist all the instant snapshots in a project,or onlylist the instant snapshots of a disk.

• For a given disk, there arelimitationsregarding the maximum number of instant snapshots and maximum time between snapshots.

Back up data across a group of disks

Preview

This product or feature is subject to the "Pre-GA Offerings Terms" in the General Service Terms section of theService Specific Terms. Pre-GA products and features are available "as is" and might have limited support. For more information, see thelaunch stage descriptions.

For workloads that use multiple disks, you can capture the data on all thedisks at the same point in time by creating a consistency group ofinstant snapshots. For example, before you make a major change to your workload,you can back up all impacted disks at once. If you need to, youcan later restore all the disks in the workload to the same point in time.

To create a consistency group of instant snapshots, you firstcreate a consistency group of the disksthat you want to back up, then createconsistency groups of instant snapshots from the group of disks. Consistencygroups of instant snapshots offer the same functionality as individualinstant snapshots, but on a larger scale.

Store an instant snapshot in a different location

You can't directly move an instant snapshot to a different location, but you cancreate a standard snapshot from an instant snapshotand store the standard snapshot in the location that you want.

Limitations

• You can't create instant snapshots of Hyperdisk Throughput or Hyperdisk ML volumes.

• You can't select the storage location of an instant snapshot.It's always stored in the same region or zone as the source disk.

• When you delete a disk, all instant snapshots of the disk are deleted,including instant snapshots that are part of a consistency group(Preview).This means that when you delete an instance, instant snapshots of theinstance's boot disk are deleted. Instant snapshots of non-boot disks attachedto the instance are also deleted ifyou'veenabled auto-delete for the disk.To retain the data on an instant snapshot before it is deleted,create a standard snapshot from the instant snapshot.

• An instant snapshot is accessible only within the zone or region where it's stored.To move an instant snapshot to another region, you must create a standard snapshotfrom the instant snapshot.

• When you create a disk from a CMEK-encrypted instant snapshot, you must providethe instant snapshot's encryption key.

• You can create a standard snapshot of an individual disk at most 6 times every60 minutes. This limit also applies to creating a standard snapshot from aninstant snapshot of a disk.

• You can't create a VM from an instant snapshot of a boot disk. Create adisk from the instant snapshot first, and choose the disk as the source for the VM.

• You can create an instant snapshot of a given disk at most once every 30seconds.

• You can't have more than 32 instant snapshots of the same disk.

• You can't create instant snapshots with snapshot schedules.

• You can't create instant snapshots on secondary asynchronouslyreplicated Persistent Disk volumes.

• Instant snapshotsarecrash consistentand not application consistent. This means that any in-memory data thathasn't yet been written to the disk isn't captured in the instant snapshot.If you require application consistency, create anapplication consistent standard snapshot.

• You can't move a disk until you delete all the instant snapshots of the disk.For more information, seeMoving a disk that has instant snapshots.

• You can't edit the data stored in an instant snapshot.

• You can't recover deleted instant snapshots.

• You can't add new instant snapshots to an existingconsistency group of instant snapshots. You must add the disk to theconsistency group of disks, then create a new consistency group of instantsnapshots using theupdated consistency group (Preview).

Billing for instant snapshots

The following costs apply to instant snapshots:

• Operation costs: Applicable at creation time for each snapshot.
• Storage costs: Charges apply based on how much data changes on the diskfrom the instant snapshot's creation until another instant snapshot is taken, oruntil the instant snapshot is deleted. The storage is billedat thesame rate as the source disk.

There are no additional costs to use consistency groups of instant snapshots(Preview).

How storage costs are calculated

Instant snapshots are billed based on the amount of data changed on the disksince the instant snapshot was taken.

The following is a summary of how costs are calculated:

• After taking an instant snapshot, there is no additional storage cost untilthe data on the source disk changes.

• For a given instant snapshot, storage costs increase as you write to the diskuntil you create another instant snapshot. Subsequent changes to the disk arebilled to the newer snapshot.

• Instant snapshots are stored as incremental resources. Whenever a block on thedisk is changed, charges accrue to the most recentinstant snapshot of that disk. If other instant snapshots had tracked changesto the same blocks, charges for those blocks only apply to the newestinstant snapshot.

Example

Suppose you create an instant snapshot,IS-1, of a disk at 9:00.At that time, the size ofIS-1 is 0 bytes.For the next 90 minutes, you write data to the disk andcreate additional instant snapshots,IS-2 andIS-3, at 9:30 and 10:15,respectively.

The total costs at 10:30 are as follows:

• Operation costs:

  • At 9:00 forIS-1.
  • At 9:30 forIS-2.
  • At 10:15 forIS-3.

• Storage costs:

  • Charges apply toIS-1 for the bytes changed on the disk from9:00 to 9:30.
  • Charges apply toIS-2 for the bytes changed on the disk from9:30 to 10:15.
  • Charges apply toIS-3 for the bytes changed on the disk from 10:15to 10:30.

If you deleteIS-3, then the storage size ofIS-2 increases to contain thebytes changed on the disk from 9:30 to 10:30. Then, if you deleteIS-2,IS-1increases to contain the bytes changed on the disk from 9:00 to 10:30.

Alternatively, if you delete onlyIS-1, the storage sizes ofIS-2 andIS-3remain the same and the bytes changed on the disk from 9:00 to 9:30 aren'ttransferred to a newer snapshot.

Instant snapshot encryption

An instant snapshot uses the same encryption as its source disk.You can't encrypt an instant snapshot with a key that is different from the keyused by the source disk.

Suppose you have a disk,D-1, that's encrypted with acustomer-supplied encryption key (CSEK) or a customer-managed encryption key (CMEK).

If you create an instant snapshot,IS-1 fromD1,IS-1 uses the same encryptionkeys asD-1. In addition, if you create a disk,D-2, fromIS-1,D-2 alsouses the same encryption keys asIS-1 andD-1.

When you create a disk from a CSEK- or CMEK-encrypted instant snapshot,you must provide the encryption keys for the source disk.

What's next

• Create an instant snapshot ofa disk.
• Back up a disk for disaster recovery withstandard snapshots.
• Learn how tocopy an instant snapshot to a standard snapshot.