Create a snapshot for a system disk or data disk to back up disk data - Elastic Compute Service

Before you perform critical operations such as rolling back disks, modifying system files, or replacing operating systems, we recommend that you create snapshots for system or data disks to back up disk data. In the event of unexpected issues or data loss, you can use the snapshots to restore data and ensure business continuity.

Note

This topic describes how to manually create a snapshot for a cloud disk.

To create snapshots for multiple cloud disks simultaneously and ensure data consistency, use snapshot-consistent groups.
To automatically create snapshots for a cloud disk on a periodic basis, use automatic snapshot policies.

Prerequisites

The snapshot service is activated. For more information, see Activate ECS Snapshot.
The cloud disk for which you want to create a snapshot is in the In Use or Unattached state.
- If the cloud disk is in the In Use state, make sure that the ECS instance to which the disk is attached is in the Running or Stopped state.
- If the cloud disk is in the Unattached status, make sure that the disk was attached to an ECS instance at least once. Snapshots cannot be created for disks that were not attached to an ECS instance at least once.
  Note
  Cloud disks that have never been attached to ECS instances do not require snapshots, as the disk data remains unchanged after the disks are created.
Snapshots can be created for the cloud disk.
Note
You cannot create snapshots for local disks or elastic ephemeral disks.

Considerations

Before you create a snapshot for a cloud disk, take note of the following items.

Item	Description
Impact on performance	Within seconds of starting the snapshot creation process, the I/O performance of the cloud disk is affected and can decrease by up to 10%. Once the snapshot upload progresses, the read and write performance of the cloud disk returns to normal. To minimize the impacts on business operations, we recommend that you create snapshots during off-peak hours or when I/O latency is not a concern.
Time required to create a snapshot	The time required to create a snapshot depends on multiple factors, such as the data volume of the snapshot, the number of snapshots being created by other users, and the snapshot size. After a snapshot is created, it is automatically stored in Object Storage Service (OSS). A longer period of time is required to upload a larger snapshot to OSS. Note The first snapshot of a cloud disk is a full snapshot and takes an extended period of time to be created. Subsequent snapshots are incremental snapshots and do not require the same amount of time to be created as the first snapshot. The amount of time required to create an incremental snapshot varies based on the amount of data changed since the previous snapshot. Early morning hours are usually the peak periods for automatic snapshot creation. The number and size of snapshots being uploaded increase during the peak periods, and the bandwidth allocated to each snapshot may decrease. As a result, a longer period of time is required to create each snapshot. To accelerate snapshot uploads, we recommend that you do not create snapshots during the peak periods. Note The initial upload time required for snapshot creation may be relatively long. However, as the number of snapshots being uploaded decreases over time, more bandwidth can be allocated to each snapshot, the transfer speed increases, and the remaining time required to upload each snapshot is reduced.
Billing	After you create snapshots, you are charged snapshot storage fees per region based on the total size of the snapshots stored in the region. For more information, see Snapshots.
Others	Do not perform operations that change the status of the associated ECS instance, such as stopping or restarting the instance. Otherwise, snapshot creation fails. While snapshots are being created, the incremental data generated by disk operations is not included in the snapshots. You cannot resize a cloud disk for which a snapshot is being created. Wait until the snapshot is created before you resize the cloud disk. When you use a cloud disk to create a logical volume or a RAID array, we recommend that you create a snapshot-consistent group and enable the application-consistent snapshot feature to ensure a consistent write order and crash consistency of data. For more information, see Snapshot consistency groups. The following limits are imposed on manual and automatic snapshots: If a snapshot is being manually or automatically created for a cloud disk when the point in time specified in the associated automatic snapshot policy is reached, the automatic snapshot cannot be created based on the policy at the point in time. An automatic snapshot is created for the disk at the next point in time specified in the automatic snapshot policy. If an automatic snapshot is being created for a cloud disk, you cannot create a manual snapshot for the disk. Wait until the automatic snapshot is created. Note For more differences between manual and automatic snapshots, see What are the differences between manual and automatic snapshots? After a snapshot is created, the snapshot is automatically stored in an OSS bucket. You cannot select an OSS bucket to store the snapshot or view the snapshot data. For more information, see Snapshot storage locations.

Procedure

This section explains how to create a snapshot for a cloud disk on the Snapshots page in the ECS console. You can also create a snapshot for a cloud disk on the Block Storage page.

Go to ECS console - Snapshots.
In the top navigation bar, select the region and resource group of the resource that you want to manage.
On the Disk Snapshots tab, click Create Disk Snapshot.

In the Create Snapshot dialog box, configure the parameters and click OK.

Parameter		Description
Resource Type		Default value: Cloud Disk, which allows you to create a snapshot for a cloud disk. Note You can also set this parameter to Instance and select one or more ECS instances to create a snapshot-consistent group. Then, select the cloud disks for which you want to create snapshots from the ECS instances to ensure disk data consistency. For more information, see Create a snapshot-consistent group.
Disk		Select the disk for which you want to create a snapshot. You can select a system disk or a data disk.
Snapshot Name		Specify a name for the snapshot.
Retention Period		Specify the retention period of the snapshot. Valid values: Permanently (Until Deleted) and Retained for. Permanently (Until Deleted): The snapshot is permanently retained and does not expire. After the maximum number of snapshots is reached, new snapshots cannot be created. Retained for: Specify a retention period in days for the snapshot. After the retention period of the snapshot ends, the snapshot expires and is automatically deleted. Note For the quotas on manual snapshots, see Overview. If you specify a retention period for a snapshot, Released After xx Days is highlighted in the Retention Period column on the Disk Snapshots tab when the snapshot is a few days, such as 3 days, away from expiration. You can extend the retention period of a snapshot before the snapshot expires. For more information, see Extend the retention period of a snapshot. To prevent unnecessary costs, we recommend that you delete unneeded snapshots at the earliest opportunity, regardless of whether the snapshots are retained permanently or for a specific number of days. For more information, see Delete a snapshot.
Advanced Settings	Instant Access	By default, the instant access feature is enabled for Enterprise SSD (ESSD) series disks (ESSDs, ESSD AutoPL disks, ESSD Entry disks, and Regional ESSDs)and is disabled for cloud disks of other categories. Note The instant access feature allows you to use snapshots for operations, such as rolling back cloud disks, creating cloud disks, or sharing snapshots, within seconds after the snapshots are created, instead of after the snapshots are uploaded to OSS. For more information, see Use the instant access feature.
	Tag	Specify tag key-value pairs for the snapshot to facilitate management.
	Resource Group	Specify a resource group to which to assign the snapshot. You can use resource groups to manage snapshots at different levels.

(Optional) View the creation progress of the snapshot on the Disk Snapshots tab.
- View the upload progress of the snapshot to OSS in the Progress column. When you move your pointer over Progress of Upload to OSS: Xx%, the estimated remaining time required to upload the snapshot is displayed.
  Note
  The estimated time to upload a snapshot to OSS may vary based on several factors. For more information, see Time required to create a snapshot section in Considerations.
  To cancel a snapshot creation task in progress, call the DeleteSnapshot operation.
- If Progress of Upload to OSS: 100% is displayed in the Progress column, the snapshot is uploaded to OSS.