Change the size of a Persistent Disk

Linux Windows

If your virtual machine (VM) instance requires additional storage space orincreased performance limits,you can increase the size of your Persistent Disk. You can increase the disk sizeat any time, whether or not the disk is attachedto a running VM.

This page discusses how to change the size of a Persistent Disk. To increase thesize of a Google Cloud Hyperdisk volume, seeModify the settings of a Hyperdisk.

Note: You can't reduce the size of a disk. For more information,seeDecrease the size of a disk.

When youcreate a custom Linux image,custom Windows image,or aFedora CoreOS image,you need to manually increase the size of the boot and non-boot disks. If you'reusing apublic image (except for Fedora CoreOS images),Compute Engine automatically resizes the boot disks.

Increasing the size of a disk doesn't delete or modify disk data, but as a bestpractice, before you make any changes to the file system or partitions, alwaysback up your disk by creating a snapshot.

Compute Engine manages the hardware behind Persistent Disks, so thatyou can add and resize your disks without handling striping or redundancy.

Important: Public Google Cloud Images don't use MBR partition typesand can only haveGPT partition types. Imported Disks withMBR partition type can only be increased to 2 TB.partitions beyond 2 TB or changing the partition type from MBR to GPT isn'tsupported. Images with MBR partitions are not supported by Cloud Customer Care.

Before you begin

Required roles and permissions

To get the permission that you need to resize a Persistent Disk, ask your administrator to grant you the following IAM roles on the project:

For more information about granting roles, seeManage access to projects, folders, and organizations.

This predefined role contains the compute.disks.update permission, which is required to resize a Persistent Disk.

You might also be able to get this permission withcustom roles or otherpredefined roles.

Decrease the size of a disk

You can't decrease the size of a Persistent Disk. You must replace the disk witha new, smaller disk. To do so, create a blank disk that has a smallersize, then copy the contents from the original disk to the new disk.You can then use the new disk instead of the original.

To replace a disk with a smaller disk, follow these steps:

  1. Create a blank Persistent Disk and specify the size you want. Make sure the new disk is large enough to contain the data from the source disk.
  2. Attach both disks to the same instance. For instructions, seeAttach a non-boot disk to a VM.
  3. Format and mount the new disk. See the instructions forLinux andWindows instances.
  4. Copy the data from the original disk to the new disk using utilities available for your operating system (OS). For example, for Linux, you can usersync ordd. For Windows instances, you can userobocopy.
  5. Verify that the new disk has all the data and is working as expected.
  6. Update your application or OS to use the new disk.
  7. After you confirm that the migration is successful, you can detach and delete the original, larger disk.
You are charged for the original disk until you delete it.

Increase the size of a disk

To increase the size of a boot or non-boot disk, use the following procedures:

Note: You can resize an Extreme Persistent Disk only once in a 6 hour period.

Console

  1. In the Google Cloud console, go to theDisks page.

    Go to Disks

  2. In the list of disks in your project, click the name of thedisk that you want to resize.

  3. On the disk details page, clickEdit. You might need toclick theMore actions menu and thenEdit.

  4. In theSize field, enter the new size for your disk. Disks with MBRpartition tables can only resize up to 2 TB.

  5. ClickSave to apply your changes to the disk.

The new disk size is displayed in the list of disks.

gcloud

Use thegcloud compute disks resizecommandand specify the--size flag with the new disk size, in gibibytes (GiB).

gcloud compute disks resizeDISK_NAME \    --sizeDISK_SIZE \    --zone=ZONE

Replace the following:

  • DISK_NAME: the name of the disk that you areresizing.
  • DISK_SIZE: the new size, in gibibytes (GiB), forthe disk. Disks with MBR partition tables can resize only up to2 TB.

  • ZONE: For zonal Persistent Disk, specify thezone where the disk is located.

    For Regional Persistent Disk, use instead the--region=REGION flag and specify the region where theregional disk is located.

Terraform

Choose one of the following options to resize either zonal disks orRegional Persistent Disk:

Zonal disk

To change the size of a Persistent Disk, you can use thegoogle_compute_disk resource and use thesize parameter.

# Using pd-standard because it's the default for Compute Engineresource "google_compute_disk" "default" {  name = "disk-data"  type = "pd-standard"  zone = "us-west1-a"  size = "5"}

If you include thesize parameter along with theimage orsnapshot parameter, thesize value must be equal to or greater than the size of the image or snapshot.

If you omit theimage andsnapshot parameters, you can set thesize parameter to less than the existing disk size. If you do this, Terraform destroys the disk and creates a new empty Persistent Disk.

Caution: To prevent Terraform from destroying and re-creating a disk, you can add thelifecycle.prevent_destroy = true setting to the Terraform configuration.

During the re-creation, Terraform doesn't copy over other data that isn't also included in the Terraform configuration, such as labels or snapshot schedules.

Regional Persistent Disk

To change the size of a Regional Persistent Disk, you can use thegoogle_compute_region_disk resource and use thesize parameter.

resource "google_compute_region_disk" "regiondisk" {  name                      = "region-disk-name"  snapshot                  = google_compute_snapshot.snapdisk.id  type                      = "pd-ssd"  region                    = "us-central1"  physical_block_size_bytes = 4096  size                      = 11  replica_zones = ["us-central1-a", "us-central1-f"]}

If you include thesize parameter along with theimage orsnapshot parameter, thesize value must be equal to or greater than the size of the image or snapshot.

If you omit theimage andsnapshot parameters, you can set thesize parameter to less than the existing disk size. If you do this, Terraform destroys the disk and creates a new empty RegionalPersistent Disk.

Caution: To prevent Terraform from destroying and re-creating a disk, you can add thelifecycle.prevent_destroy = true setting to the Terraform configuration.

During the re-creation, Terraform doesn't copy over other data that isn't also included in the Terraform configuration, such as labels or snapshot schedules.

REST

To resize a Persistent Disk, construct aPOST request to thecompute.disks.resize method.

POST https://compute.googleapis.com/compute/v1/projects/PROJECT_ID/zones/ZONE/disks/DISK_NAME/resize{  "sizeGb": "DISK_SIZE"}

To resize a Regional Persistent Disk, construct aPOST request to thecompute.regionDisks.resize method.

POST https://compute.googleapis.com/compute/v1/projects/PROJECT_ID/regions/REGION/disks/DISK_NAME/resize{   "sizeGb": "DISK_SIZE"}

Replace the following:

  • PROJECT_ID: your project ID.
  • ZONE: For zonal Persistent Disk: the zone where thedisk is located.
  • REGION: For Regional Persistent Disk: the regionwhere the disk is located.
  • DISK_NAME: the name of the disk to resize.
  • DISK_SIZE: the new size, in gibibytes (GiB), forthe disk. Disks with MBR partition tables can resize only up to 2 TB.

Resize the file system and partitions

After increasing the size of a disk, you might need to resize its file systemand partitions. The following list shows additional information for boot andnon-boot disks:

  • Boot disk: If you're usinga custom Linux image,custom Windows image,or aFedora CoreOS image,you must manually resize the root partition and file system. For VMs withpublic images (except for Fedora CoreOS images),Compute Engine automatically resizes the root partition and filesystem after you increase the size of the boot disk and you don't need torestart the VM.

  • Non-boot disk: After increasing the size of the disk, you must extend thefile system on the disk to use the added space. You don't need to restart theVM.

The following example shows how to manually resize the root partition and filesystem of a boot disk, and how to manually resize the file system of a non-bootdata disk with no partition table. This example assumes that the diskis attached using SCSI and was previously formatted and mounted.

If your Persistent Disk was attached using NVMe, seeResize the file system and partitionsfor example output for NVMe-attached disks.

Linux VMs

  1. In the Google Cloud console, go to theVM instances page.

    Go to VM instances

  2. Next to the instance that has the new attached disk, click theSSHbutton. The browser opens a terminal connection to the instance.

  3. Use thedf and thelsblk commands to list the size of the file systemand to find the device names for your disks.

    $sudo df -ThFilesystem      Type     Size   Used  Avail  Use%  Mounted on/dev/sda1       ext4     9.7G   1.2G   8.5G   12%  //dev/sdb        ext4     250G    60M   250G    1%  /mnt/disks/disk-1
    $sudo lsblkNAME    MAJ:MIN RM  SIZE RO TYPE MOUNTPOINTsda       8:0    0   20G  0 disk└─sda1    8:1    0   10G  0 part /sdb       8:16   0  500G  0 disk /mnt/disks/disk-1

    This example includes the following disks:

    • Boot disk: The/dev/sda1 partition is on a boot disk that hasbeen resized to 20 GB. The partition table and the file system provideonly 9.7 GB to the operating system.
    • Non-boot data disk: The/dev/sdb non-boot data disk has nopartition table, but the file system on that disk provides only 250 GBto the operating system. The mount directory for this disk is/mnt/disks/disk-1.

    Thedf command shows that the/dev/sda1 partition is mounted as theroot file system, and the/dev/sdb disk is mounted as a non-boot datadisk at/mnt/disks/disk-1. Make note of theType column, whichindicates if your disk uses anext4 orxfs file system.

  4. Verify the partition type:

    sudo parted -l
    Alternatively, to see information only for a specific disk:
    sudo parted -l /dev/DEVICE_NAME
    Look for the fieldPartition Table. If the value ismsdos, thenthe disk has an MBR partition type. This means the maximum size of such adisk is 2 TB.

  5. Resize the root partition and file system on the boot disk. This exampleassumes the VM image does not support automatic root partitioning andfile system resizing.

    1. Resize the root partition by usingparted. For example, thefollowing commands expand partition1 of/dev/sda to the maximumpossible size:

      1. Openparted on the/dev/sda partition:

        sudo parted /dev/sda

      2. At the(parted) prompt, enter:

        resizepart

      3. At thePartition number? prompt, enter:

        1

      4. At theWarning: Partition /dev/sda1 is being used. Are you sureyou want to continue? prompt, enter:

        Yes

      5. At theEnd? prompt, enter

        100%

      6. At the(parted) prompt, enter:

        quit

    2. Read the new partition table usingpartprobe.

      sudo partprobe /dev/sda

    3. Extend the file system:

      • If you are usingext4, use theresize2fs command:

        sudo resize2fs /dev/sda1

      • If you are usingxfs, use thexfs_growfs command:

        sudo xfs_growfs -d /

      • If you are usingbtrfs,use thebtrfs command:

        sudo btrfs filesystem resize max /

  6. Resize the file system on the non-boot data disk.

    • If you are usingext4, use theresize2fs command to extend thefile system:

      sudo resize2fs /dev/DEVICE_NAME

      ReplaceDEVICE_NAME with the device name forthe disk. In this example, the device name is/dev/sdb.

    • If you are usingxfs, use thexfs_growfs command to extend thefile system:

      sudo xfs_growfsMOUNT_DIR

      ReplaceMOUNT_DIR with the mount point of the device. Youcan find the mount point listed in theMOUNTPOINT column in theoutput of thelsblk command.

    • If you are usingbtrfs,use thebtrfs command to extend the file system:

      sudo btrfs filesystem resize maxMOUNT_DIR

      ReplaceMOUNT_DIR with the mount point of the device. Youcan find the mount point listed in theMOUNTPOINT column in theoutput of thelsblk command.

  7. Use thedf command to verify that the file system is extended. Forexample:

    df -h /dev/sdbFilesystem  Size  Used  Avail  Use%  Mounted on/dev/sdb    493G   70M  492G     1%  /mnt/disks/disk-1

Windows VMs

Use theWindows Disk Management utility to resize partitions on a Windows instance.

  1. In the Google Cloud console, go to theVM instances page.

    Go to VM instances

  2. Next to the instance that has the resized disk, click theRDP button.The browser opens an RDP connection to the instance.

  3. Right-click the Windows Start button and selectDisk Management toopen the Disk Management tool.

    Selecting the Windows Disk Manager tool from the right-click menu on the Windows Start button.

  4. Show the disks partition type by running in Powershell:

    Get-Disk
    In thePartition Style column, if the value isMBR then thedisk has an MBR partition type. This means themaximum size of such a disk would be 2 TB.

  5. Refresh the Disk Management tool so that it recognizes the additionalspace on your zonal Persistent Disk. At the top of the Disk Managementwindow, clickAction and selectRefresh.

    Clicking the Action menu and selecting Refresh to update the zonal Persistent Disk information in the Disk Management tool.

  6. On the disk that you resized, right-click the formatted partition andselectExtend Volume.

    Right-clicking the formatted portion of the disk and selecting the Extend Volume option.

  7. Follow the instructions in theExtend Volume Wizard to extend yourexisting partition to include the extra disk space. If the existingpartition is formatted in NTFS, the maximum partition size islimited byits cluster size settings.

  8. After you complete the wizard and the volume finishes formatting, checktheStatus column on the list of attached disks to ensure that the newdisk has aHealthy status.

    Viewing the list of disks that are recognized by Windows, verify that the instance is Online with a Healthy status.

You don't need to restart your VM after you complete this process. Youcan now use the added disk space to store data.

What's next

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Last updated 2026-02-18 UTC.