Modify the size of a Persistent Disk

Linux Windows

If your Compute Engine virtual machine (VM) instance needs additional storage space or increased performance limits, you can increase the size of your Persistent Disk. You can increase the disk size at any time, whether or not the disk is attached to a running VM.

This page discusses how to change the size of a Persistent Disk. To increase the size of a Google Cloud Hyperdisk volume, see Modify the size and provisioned performance of a Hyperdisk volume.

Important: You can't reduce the size of a disk. For more information, see Decrease the size of a disk.

When you create a custom Linux image, custom Windows image, or a Fedora CoreOS image, you need to manually increase the size of the boot and non-boot disks. If you're using a public 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 best practice, before you make any changes to the file system or partitions, always back up your disk by creating a snapshot.

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

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

Before you begin

• If you haven't already, set up authentication. Authentication verifies your identity for access to Google Cloud services and APIs. To run code or samples from a local development environment, you can authenticate to Compute Engine by selecting one of the following options:

  Select the tab for how you plan to use the samples on this page:

  Console

  When you use the Google Cloud console to access Google Cloud services and APIs, you don't need to set up authentication.

  gcloud

  1. Install the Google Cloud CLI. After installation, initialize the Google Cloud CLI by running the following command:

     gcloud init

     If you're using an external identity provider (IdP), you must first sign in to the gcloud CLI with your federated identity.

     Note: If you installed the gcloud CLI previously, make sure you have the latest version by running gcloud components update.
  2. Set a default region and zone.

  Terraform

  To use the Terraform samples on this page in a local development environment, install and initialize the gcloud CLI, and then set up Application Default Credentials with your user credentials.

  1. Install the Google Cloud CLI.

  2. If you're using an external identity provider (IdP), you must first sign in to the gcloud CLI with your federated identity.

  3. If you're using a local shell, then create local authentication credentials for your user account:

     gcloud auth application-default login

     You don't need to do this if you're using Cloud Shell.

     If an authentication error is returned, and you are using an external identity provider (IdP), confirm that you have signed in to the gcloud CLI with your federated identity.

  For more information, see Set up authentication for a local development environment.

  REST

  To use the REST API samples on this page in a local development environment, you use the credentials you provide to the gcloud CLI.

  Install the Google Cloud CLI.

  If you're using an external identity provider (IdP), you must first sign in to the gcloud CLI with your federated identity.

  For more information, see Authenticate for using REST in the Google Cloud authentication documentation.

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:

• Compute Instance Admin (v1) (roles/compute.instanceAdmin.v1)
• To connect to a VM that can run as a service account: Service Account User (v1) (roles/iam.serviceAccountUser)

For more information about granting roles, see Manage 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 with custom roles or other predefined roles.

Decrease the size of a disk

You can't decrease the size of a Persistent Disk. You must replace the disk with a new, smaller disk. To do so, create a blank disk that has a smaller size, 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, see Attach a non-boot disk to a VM.
3. Format and mount the new disk. See the instructions for Linux and Windows 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 use rsync or dd. For Windows instances, you can use robocopy.
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.

Size limits for Persistent Disk volumes

The size you specify for a Persistent Disk volume must be within the ranges listed in following table.

Disk type	Minimum size	Maximum size	Default size
Balanced Persistent Disk	Zonal: 10 GiB Regional: 10 GiB	64 TiB	100 GiB
Performance (SSD) Persistent Disk	Zonal: 10 GiB Regional: 10 GiB	64 TiB	100 GiB
Standard Persistent Disk	Zonal: 10 GiB Regional: 200 GiB	64 TiB	500 GiB
Extreme Persistent Disk	500 GiB	64 TiB	1 TiB

Increase the size of a Persistent Disk volume

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 the Disks page.

   Go to Disks

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

3. On the disk details page, click Edit. You might need to click the More actions menu and then Edit.

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

5. Click Save to apply your changes to the disk.

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

gcloud

Use the gcloud compute disks resizecommand and specify the --size flag with the new disk size, in gibibytes (GiB).

gcloud compute disks resize DISK_NAME \
    --size DISK_SIZE \
    --zone=ZONE

Replace the following:

• DISK_NAME: the name of the disk that you are resizing.
• DISK_SIZE: the new size, in gibibytes (GiB), for the disk. Disks with MBR partition tables can resize only up to 2 TB.

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

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

Terraform

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

Zonal disk

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

# Using pd-standard because it's the default for Compute Engine

resource "google_compute_disk" "default" {
  name = "disk-data"
  type = "pd-standard"
  zone = "us-west1-a"
  size = "5"
}

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

If you omit the image and snapshot parameters, you can set the size 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 the lifecycle.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 the google_compute_region_disk resource and use the size 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 the size parameter along with the image or snapshot parameter, the size value must be equal to or greater than the size of the image or snapshot.

If you omit the image and snapshot parameters, you can set the size 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 the lifecycle.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.

To learn how to apply or remove a Terraform configuration, see Basic Terraform commands.

REST

To resize a Persistent Disk, construct a POST request to the compute.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 a POST request to the compute.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 the disk is located.
• REGION: For Regional Persistent Disk: the region where the disk is located.
• DISK_NAME: the name of the disk to resize.
• DISK_SIZE: the new size, in gibibytes (GiB), for the disk. Disks with MBR partition tables can resize only up to 2 TB.

Resize the file system and partitions

After you increase the size of a disk, you might need to resize its file system and partitions. The following is additional information for boot and non-boot disks:

• Boot disks: If you're using a custom Linux image, custom Windows image, or a Fedora CoreOS image, you must manually resize the root partition and file system. For instances with public images (except for Fedora CoreOS images), Compute Engine automatically resizes the root partition and file system after you increase the size of the boot disk and you don't need to restart the instance.

• Non-boot disks: After increasing the size of the disk, you must extend the file system on the disk to use the added space.

The following examples shows how to manually resize the root partition and file system of a boot disk, and how to manually resize the file system of a non-boot data disk with no partition table. Both examples assume that the attached disks were previously formatted and mounted.

Linux instances

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

   Go to VM instances

2. Find the instance that the disk that you resized is attached to. Click SSH. The browser opens a terminal connection to the instance.

3. Use the df and lsblk commands to list the size of the file system and find the device names for your disks.

   $ sudo df -Th
   
   Filesystem      Type      Size  Used Avail Use% Mounted on
   udev            devtmpfs  3.9G     0  3.9G   0% /dev
   /dev/nvme0n1p1  ext4      9.7G  2.0G  7.2G  22% /
   /dev/nvme0n1p15 vfat      124M   12M  113M  10% /boot/efi
   /dev/nvme0n2    ext4       98G   24K   98G   1% /mnt/disks/data
   
   

   $ sudo lsblk
   
   NAME        MAJ:MIN   RM  SIZE RO TYPE MOUNTPOINT
   nvme0n1      259:0    0   20G  0 disk
   ├─nvme0n1p1  259:5    0  9.9G  0 part /
   ├─nvme0n1p14 259:6    0    3M  0 part
   └─nvme0n1p15 259:7    0  124M  0 part /boot/efi
   nvme0n2      259:4    0  100G  0 disk /mnt/disks/data
   
   

   This example includes the following disks:

   • Boot disk: The /dev/nvme0n1p1 partition is on a boot disk that has been resized to 20 GB. The partition table and the file system provide only 9.9 GB to the operating system.
   • Non-boot data disk: The /dev/nvme0n2 non-boot data disk has no partition table, but the file system on that disk provides 100 GB to the operating system. The mount directory for this disk is /mnt/disks/data.

   Make note of the Type column in the df command output, which indicates if your disk uses an ext4 or xfs file system.

   Note: This example assumes the disk is attached to the instance using the NVMe interface. If the disk is attached using the SCSI interface, the partition names for a single disk are of the form /dev/sda1, /dev/sda2, and not /dev/nvme0n1p1, /dev/nvme0n1p14.

4. Verify the partition type:

   sudo parted -l
   

   The first time you run this command after resizing a disk, you might see a message similar to the following:

   Warning: Not all of the space available to /dev/nvme0n1 appears to be
   used, you can fix the GPT to use all of the space (an extra 20971520
   blocks) or continue with the current setting?
   Fix/Ignore?
   

   If you enter Fix, the OS will automatically repartition the disk to make the additional space available to the OS. Skip ahead to the last step if you don't have any additional disks to modify.

5. If you choose not to use the automatic fix option, or it isn't available, view the information for the disk you want to repartition:

   sudo parted -l /dev/DEVICE_NAME
   

   Look for field: Partition Table, if the value is msdos then the disk has an MBR partition type. This means the maximum size of such a disk would be 2 TB.

6. For a boot disk, resize the root partition and file system on the disk. This example assumes the VM image does not support automatic root partitioning and file system resizing.

   1. Resize the root partition by using parted. For example, the following commands expand partition 1 of the device to the maximum possible size:

      1. Open parted on the device:

         sudo parted /dev/DEVICE_NAME
         

         Replace DEVICE_NAME with the device name for the boot disk, for example, nvme0n1

      2. At the prompt, enter:

         (parted) resizepart
         

      3. At the Partition number? prompt, enter:

         1
         

      4. At the Warning: Partition /dev/DEVICE_NAMEp1 is being used. Are you sure you want to continue? prompt, enter:

         Yes
         

      5. At the End? prompt, enter

         100%
         

      6. At the (parted) prompt, enter:

         (parted) quit
         

   2. View the new partition table using parted -l.

      sudo parted -l /dev/DEVICE_NAME
      
      Model: nvme_card-pd (nvme)
      Disk /dev/DEVICE_NAME: 21.5GB
      Sector size (logical/physical): 512B/512B
      Partition Table: gpt
      Disk Flags:
      
      Number  Start   End     Size    File system  Name  Flags
      14      1049kB  4194kB  3146kB                     bios_grub
      15      4194kB  134MB   130MB   fat16              boot, esp
      1       134MB   21.5GB  21.3GB  ext4
      

   3. Extend the file system:

      • If you are using ext4, then use the resize2fs command:

        sudo resize2fs /dev/PARTITION_NAME
        

        Replace PARTITION_NAME with the partition name for the boot disk, for example, nvme0n1p1.

      • If you are using xfs, then use the xfs_growfs command:

        sudo xfs_growfs -d /
        

      • If you are using btrfs, then use the btrfs command:

        sudo btrfs filesystem resize max /
        

7. For a non-boot data disk, resize the file system on the disk.

   • If you are using ext4, then use the resize2fs command to extend the file system:

     sudo resize2fs /dev/PARTITION_NAME
     

     Replace PARTITION_NAME with the partition name for the data disk. In this example, the partition name is /dev/nvme0n2p1.

   • If you are using xfs, use the xfs_growfs command to extend the file system:

     sudo xfs_growfs MOUNT_DIR
     

   • If you are using btrfs, use the btrfs command to extend the file system:

     sudo btrfs filesystem resize max MOUNT_DIR
     

     Replace MOUNT_DIR with the mount point of the device. You can find the mount point listed in the MOUNTPOINT column in the output of the lsblk command.

8. Use the df command to verify that the file system is extended. For example:

   df -h /dev/PARTITION_NAME
   
   Filesystem       Size  Used  Avail    Use%     Mounted on
   /dev/nvme0n2p1   118G  70M   118G     1%     /mnt/disks/data
   

Windows VMs

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

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

   Go to VM instances

2. Find the instance that has the resized disk. Click the RDP button for the instance. The browser opens an RDP connection to the instance.

3. Right-click the Windows Start button and select Disk Management to open the Disk Management tool.

   

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

   Get-Disk
   

   In the Partition Style column, if the value is MBR then the disk has an MBR partition type. This means the maximum size of such a disk would be 2 TB.

5. Refresh the Disk Management tool so that it recognizes the additional space on the disk. At the top of the Disk Management window, click Action and select Refresh.

   

6. On the disk that you resized, right-click the formatted partition and select Extend Volume.

   

7. Follow the instructions in the Extend Volume Wizard to extend your existing partition to include the extra disk space. If the existing partition is formatted in NTFS, then the maximum partition size is limited by its cluster size settings.

8. After you complete the Extend Volume Wizard and the volume finishes formatting, check the Status column on the list of attached disks to ensure that the new disk has a Healthy status.

   

You don't need to restart your instance after you complete this process. You can start using the added disk space.

What's next

• Troubleshooting full disks and disk resizing