Creating persistent disk snapshots

Create snapshots to periodically back up data from your zonal persistent disks or regional persistent disks. To reduce the risk of unexpected data loss, consider the best practice of setting up a snapshot schedule to ensure your data is backed up on a regular schedule.

If you want to delete a snapshot or if you want to restore the data from a snapshot to a persistent disk, see Restoring and deleting persistent disk snapshots.

You can create snapshots from disks even while they are attached to running instances. Snapshots are global resources, so any snapshot is accessible by any resource within the same project. You can also share snapshots across projects by granting users in other projects access to snapshot resources.

Note that snapshots are different from public images and custom images, which are primarily used to create boot disks for instances or to configure the boot disks for instance templates.

Compute Engine stores multiple copies of each snapshot across multiple locations with automatic checksums to ensure the integrity of your data.

Before you begin

• If you want to use the command-line examples in this guide:
  1. Install or update to the latest version of the gcloud command-line tool.
  2. Set a default region and zone.
• If you want to use the API examples in this guide, set up API access.
• Read about persistent disks.
• Review the best practices for creating snapshots.

Permissions required for this task

To perform this task, you must have the following permissions:

• compute.disks.createSnapshot on the disk
• compute.disks.addResourcePolicies on the disk
• compute.snapshots.delete on the snapshot
• compute.resourcePolicies.create on the resource policy
• compute.resourcePolicies.delete on the resource policy

Restrictions

• You cannot change the storage location of an existing snapshot. See Selecting the storage location for a snapshot.

• You can snapshot your disks at most once every 10 minutes. If you want to issue a burst of requests to snapshot your disks, you can issue at most 6 requests in 60 minutes. For more information, see Snapshot frequency limits.

Important: If you create a VM instance from a disk snapshot based on a Shielded VM image, the original integrity policy baseline is lost and the first set of boot sequence measurements on the new VM instance is used as the new baseline. Because this new set of measurements is not verified, validate the VM instance's boot integrity after restoring from a snapshot. You can do this by manually examining the boot log and verifying that the proper keys are loaded into the SecureBoot database, and that the expected kernel version is running. Also, secrets saved in the vTPM on the originating VM instance are not accessible on VM instances restored from a snapshot of that instance.

How incremental snapshots work

Snapshots are incremental and automatically compressed, so you can create regular snapshots on a persistent disk faster and at a much lower cost than if you regularly created a full image of the disk. Incremental snapshots work in the following manner:

• The first successful snapshot of a persistent disk is a full snapshot that contains all the data on the persistent disk.
• The second snapshot only contains any new data or modified data since the first snapshot. Data that hasn't changed since snapshot 1 isn't included. Instead, snapshot 2 contains references to snapshot 1 for any unchanged data.
• Snapshot 3 contains any new or changed data since snapshot 2 but won't contain any unchanged data from snapshot 1 or 2. Instead, snapshot 3 contains references to blocks in snapshot 1 and snapshot 2 for any unchanged data.

This repeats for all subsequent snapshots of the persistent disk. Snapshots are always created based on the last successful snapshot taken.

Important: Snapshots are incremental by default to avoid billing you for redundant data and to minimize use of storage space. However, to ensure the reliability of snapshot history, a snapshot might occasionally capture a full image of the disk.

Using the gcloud tool or the Compute Engine API, you can create snapshots in distinct snapshot chains by specifying a snapshot chainName. When you create multiple snapshots of a persistent disk using a chain name, each snapshot is based incrementally on the last successful snapshot created with that chain name. This is available in beta. Use this field only if you are an advanced service owner who needs to create separate snapshot chains, for example, for chargeback tracking.

Listing snapshots in your project

To see a list of snapshots available to a project, use the gcloud compute snapshots list command:

gcloud compute snapshots list

Viewing information about a snapshot

To list information about a particular snapshot, such as the creation time, size, and source disk, use the gcloud compute snapshots describe command:

gcloud compute snapshots describe [SNAPSHOT_NAME]

where [SNAPSHOT_NAME] is the name of the snapshot for which you want to see the snapshot information.

Selecting the storage location for a snapshot

When you create a snapshot, you can specify a storage location. The location of a snapshot affects its availability and can incur networking costs when creating the snapshot or restoring it to a new disk.

Snapshots can be stored in either one Cloud Storage multi-regional location, such as asia, or one Cloud Storage regional location, such as asia-south1.

A multi-regional storage location provides higher availability and might reduce network costs when creating or restoring a snapshot. For example, creating a disk from a snapshot stored in a multi-regional location does not incur network costs as long as the new persistent disk is created in one of the regions of the multi-regional group. A regional storage location gives you more control over the physical location of your data because you specify a single region.

A snapshot can be used to create a new disk in any region and zone, regardless of the storage location of the snapshot.

If you have an organization policy that includes the resource locations constraint, any snapshot storage location that you specify must be in the set of locations defined by the constraint. See Compute Engine resource locations for more information.

If you do not specify a storage location for a snapshot, Google Cloud uses the default location, which stores your snapshot in a Cloud Storage multi-regional location closest to the region of the source disk. If you need to choose regional storage, or if you need to specify a different multi-regional location, store your snapshot in a custom location.

Note: You cannot change the storage location of an existing snapshot. If you need to move a snapshot from one region or multi-regional location to another, you must create a new snapshot and specify its location, and delete the previous snapshot. When you create a snapshot, you can only specify one multi-regional location or one regional location. If you need to store a snapshot in more than one location, you must create a snapshot in each location.

Default location

If you do not specify a storage location, your snapshot is stored in the multi-region that is geographically closest to the location of your persistent disk.

For example, if your persistent disk is stored in us-central1, your snapshot is stored in the us multi-region by default.

However, a default location like australia-southeast1 is outside of a multi-region. The closest multi-region is asia. Creating or restoring a snapshot generates network costs.

Some example use cases for choosing a default location to store your snapshots are:

• The default multi-region location meets corporate or government data-placement policies.
• Your persistent disk is stored in a regional location that is part of a default multi-region location. For example, your persistent disk is in the us-central1 region, so the default multi-region is us. In this case, you want to prioritize higher snapshot availability over potentially slower snapshot restoration performance.
• You do not expect your snapshots to be frequently restored to disks that are located outside of the default snapshot storage location.

Custom location

Select a custom location to store your snapshot in a regional location, or if you need to specify a different multi-regional location.

Some example cases for selecting a custom storage location for your snapshots are:

• The custom multi-region location meets corporate or government data-placement policies.
• Your app is deployed in a region that is not included in one of the Cloud Storage multi-regional locations and you want to prioritize snapshot restoration performance over snapshot availability.
• You restore your snapshots multiple times from a disk located outside of the default snapshot storage location.

If you need to comply with corporate or government data-placement policies, store your snapshot in the nearest regional location that complies with these policies.

If your app is not deployed in part of a multi-region and you want to prioritize low networking costs over high snapshot availability, store your snapshot in the region where your source disk is located. Storing your snapshot in the region where your source disk is located minimizes networking costs for restoring and creating snapshots from that source disk.

However, unlike a multi-regional storage location, a regional storage location doesn't store your data redundantly across multiple data centers, so your data might not be accessible if a large-scale disruption occurs. To ensure the availability of your data, you might also want to store a redundant snapshot in a second location.

Network costs

Selecting your snapshot storage location is vital to minimizing network costs. If you store your snapshot in the same region as your source disk there is no network charge when you access that snapshot from the same region. If you access the snapshot from a different region, there is a network cost.

If your source disk's geographic storage location is the same as its multi-region, there is no network charge.

For example, if your source disk is in asia-east1-a you can store your snapshot in the asia-east1 region or the asia multi-region. You won't incur a network cost when you access your snapshots.

There is a network charge for cross-region access. For example, if your source disk is in asia-east1 and you store your snapshots in asia-east2, you will incur a network cost when you access your snapshot between those two regions.

Two regions, australia-southeast1 and southamerica-east1, have a default multi-region snapshot storage location that will incur network costs unless you override the default when creating a snapshot.

• If your source disk is in australia-southeast1, the default snapshot storage location is in the asia multi-region. To reduce costs, override this default location and store your snapshots in the australia-southeast1 region.
• If your source disk is in southamerica-east1, the default snapshot storage location is in the us multi-region. To reduce costs, override this default location and store your snapshots in the southamerica-east1 region.

If you restore a snapshot to a disk in a region that isn't included in the snapshot's storage location you will incur a network cost. For example, if you create a new regional persistent disk in australia-southeast1 from a snapshot stored in asia, a multi-regional location, you will incur network costs.

Creating a snapshot

In preparation for creating persistent disk snapshots, do the following:

• Review Best practices for persistent disk snapshots to prepare your disk for snapshotting.

• Read Creating a persistent disk snapshot schedule to learn about creating a snapshot schedule and attaching it to your disks.

• For instructions about how to create snapshots from disks that are encrypted with your own encryption keys, see Creating a snapshot from an encrypted disk.

• For instructions about how to create a Windows persistent disk snapshot, see Creating a Windows persistent disk snapshot.

Creating a snapshot of a zonal persistent disk

After you have prepared the disk, you can create a snapshot. Follow these steps to take a snapshot of a zonal persistent disk. If the persistent disk that you want to use is located in multiple zones, follow the instructions for creating a snapshot of a regional persistent disk.

Console

1. Go to the Create a Snapshot page in the Google Cloud Console.
   Go to the Create a Snapshot page
2. Enter a snapshot Name.
3. Optionally, enter a Description of the snapshot.
4. Select the Source disk from the drop-down menu.

5. Determine your snapshot storage location. You can use the default storage location, or a custom storage location.

   1. Under Location, select whether you want to store your snapshot in a Multi-regional location or a Regional location.
   2. Select which specific region or multi-region that you want to use. To use the region or multi-region that is closest to your source disk, select Based on disk's location (default).

6. Click Create to create the snapshot.

gcloud

Create your snapshot in the default storage location or in a selected storage location. Optionally, you can specify a snapshot name with the --snapshot-names flag. The default snapshot name is a random 12-character alphanumeric string that starts with a letter.

• To create a snapshot of a zonal persistent disk in the default storage location, use the gcloud compute disks snapshot command:

  gcloud compute disks snapshot [DISK_NAME]
  

  where:

  • [DISK_NAME] is the name of the zonal persistent disk from which you want to create a snapshot.

• Alternatively, to create a snapshot in a custom storage location, use the --storage-location flag to indicate where to store your snapshot:

  gcloud compute disks snapshot [DISK_NAME] \
      --storage-location [STORAGE_LOCATION]
  

  where:

  • [DISK_NAME] is the name of the zonal persistent disk from which you want to create a snapshot.
  • [STORAGE_LOCATION] is the Cloud Storage multi-region or the Cloud Storage region where you want to store your snapshot. You can specify only one storage location.

The gcloud command-line tool waits until the operation returns a status of READY or FAILED, or reaches the maximum timeout and returns the last known details of the snapshot.

API

Create your snapshot in the default storage location or in a selected storage location. Optionally, you can specify a snapshot name with the name field. The default snapshot name is a random 12-character alphanumeric string that starts with a letter.

• To create your snapshot in the default storage location, make a POST request to the disks.createSnapshot method:

  POST https://compute.googleapis.com/compute/v1/projects/[PROJECT_ID]/zones/[ZONE]/disks/[DISK_NAME]/createSnapshot
  

  where:

  • [PROJECT_ID] is your project ID.
  • [ZONE] is the zone where your instance and disk are located.
  • [DISK_NAME] is the name of the zonal persistent disk from which you want to create a snapshot.

• Alternatively, to create a snapshot in a custom storage location, make a POST request to the disks.createSnapshot method and specify the storage location:

  POST https://compute.googleapis.com/compute/v1/projects/[PROJECT_ID]/zones/[ZONE]/disks/[DISK_NAME]/createSnapshot
  
  {
    "storageLocations": [STORAGE_LOCATION]
  }
  

  where:

  • [PROJECT_ID] is your project ID.
  • [ZONE] is the zone where your instance and disk are located.
  • [DISK_NAME] is the name of the zonal persistent disk from which you want to create a snapshot.
  • [STORAGE_LOCATION] is the Cloud Storage multi-region or the Cloud Storage region where you want to store your snapshot. You can specify only one storage location.

Caution: If you attempt to create a snapshot from a zonal persistent disk and the snapshotting process fails, you won't be able to delete the original zonal persistent disk until you have cleaned up the failed snapshot. This failsafe helps to prevent the accidental deletion of source data in the event of an unsuccessful backup.

Create a snapshot of a regional persistent disk

After you have prepared the disk, you can create a snapshot. When creating a snapshot of a regional persistent disk, you must indicate the region where the disk is located.

Console

1. Go to the Create a Snapshot page in the Google Cloud Console.
   Go to the Create a Snapshot page
2. Enter a snapshot Name.
3. Optionally, enter a Description of the snapshot.
4. Under Source disk, select an existing disk from which you want to create a snapshot.

5. Optionally, you can specify a custom storage location:

   1. Under Location, select whether you want to store your snapshot in a Multi-regional location or a Regional location.
   2. Select which specific region or multi-region that you want to use. To use the region or multi-region that is closest to your source disk, select Based on disk's location.

6. Click Create to create the snapshot.

gcloud

Create your snapshot in the default storage location or in a selected storage location.

• To create a snapshot of a regional persistent disk in the default storage location, use the gcloud compute disks snapshot command:

  gcloud compute disks snapshot [DISK_NAME] \
      --region [REGION]
  

  where:

  • [DISK_NAME] is the name of the regional persistent disk from which you want to create a snapshot.
  • [REGION] is the region where your regional persistent disk is located.

• Optionally, you can specify a custom storage location:

  gcloud compute disks snapshot [DISK_NAME] --region [REGION] \
      --storage-location [STORAGE_LOCATION]
  

  where:

  • [DISK_NAME] is the name of the regional persistent disk from which you want to create a snapshot.
  • [REGION] is the region where your regional persistent disk is located.
  • [STORAGE_LOCATION] is the Cloud Storage multi-region or the Cloud Storage region where you want to store your snapshot. You can specify only one storage location.

  The gcloud command-line tool waits until the operation returns a status of READY, FAILED, or reaches the maximum timeout and returns the last known details of the snapshot.

API

• To create a snapshot in the default storage location, make a POST request to the regionDisk.createSnapshot method:

  POST https://compute.googleapis.com/compute/v1/projects/[PROJECT_ID]/regions/[REGION]/disks/[DISK_NAME]/createSnapshot
  

  where:

  • [PROJECT_ID] is your project ID.
  • [REGION] is the region where your regional persistent disk is located.
  • [DISK_NAME] is the name of the disk you want to snapshot.

• Alternatively, to create a snapshot in a custom storage location, make a POST request to the regionDisk.createSnapshot method and specify the storage location:

  POST https://compute.googleapis.com/compute/v1/projects/[PROJECT_ID]/regions/[REGION]/disks/[DISK_NAME]/createSnapshot
  {
   "storageLocations": [STORAGE_LOCATION]
  }
  

  where:

  • [PROJECT_ID] is your project ID.
  • [REGION] is the region where your regional persistent disk is located.
  • [DISK_NAME] is the name of the regional persistent disk from which you want to create a snapshot.
  • [STORAGE_LOCATION] is the Cloud Storage multi-region or the Cloud Storage region where you want to store your snapshot. You can specify only one storage location.

Caution: If you attempt to create a snapshot from a regional persistent disk and the snapshotting process fails, you won't be able to delete the original regional persistent disk until you capture a clean snapshot. This failsafe prevents the accidental deletion of source data in the event of an unsuccessful backup.

What's next

• Learn how to create a snapshot schedule for persistent disks.
• Learn how to restore and delete snapshots.
• Learn how to manage access to snapshots.
• Learn how to create a disk image from your snapshot.
• Learn how to share snapshots across projects.