Create a snapshot for a single system disk or data disk to back up cloud disk data-Elastic Compute Service(ECS)-阿里云帮助中心

Before you perform critical operations, such as rolling back a cloud disk, modifying key system files, or changing the operating system, create a snapshot for the cloud disk (system disk or data disk) to back up data. If unexpected issues or data loss occurs during an operation, you can use the snapshot to restore data and ensure business continuity.

Note

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

To create snapshots for multiple cloud disks at the same time and ensure data consistency, use a snapshot consistency group.
To automatically and periodically create snapshots for a single cloud disk, use an automatic snapshot policy.

Prerequisites

The snapshot feature is enabled. For more information, see Enable snapshots.
Ensure the cloud disk is in the In Use or Pending state.
- If the cloud disk is In Use, the instance to which the disk is attached must be in the Running or Stopped state.
- If the cloud disk is in the Pending state, it must have been previously attached to an ECS instance. Snapshots cannot be created for a cloud disk that has never been attached to an instance.
  
  Note
  Snapshots are unnecessary for a cloud disk that has never been attached to an ECS instance, as its data has not changed.
Ensure the cloud disk supports snapshot creation.

Note
ESSD PL-X云盘、You cannot create snapshots for local disks or elastic ephemeral disks.

Considerations

Before you create a snapshot, consider the following:

Consideration	Description
Impact on performance	When you create a snapshot, the I/O performance of the cloud disk may drop by up to 10% for a few seconds. After the snapshot starts uploading, the disk's read and write performance returns to normal. Create snapshots during off-peak hours or when your workload is not sensitive to I/O latency to minimize the impact on your business.
Creation time	The time required to create a snapshot depends on factors such as the amount of data, the number of other snapshots being created concurrently, and the total snapshot size. After creation, snapshots are stored by default in a hidden Object Storage Service (OSS) bucket. The larger the data size of a snapshot, the longer it takes to upload to OSS. Note The first snapshot of a cloud disk is a full snapshot and takes a longer time to create. Subsequent snapshots are incremental snapshots and take less time. However, the creation time still depends on the amount of data that has changed since the last snapshot was created. The more data that has changed, the longer it takes. Automatic snapshot creation often peaks around midnight. During this period, the number and total size of snapshots being uploaded increase, which may reduce the bandwidth allocated to each snapshot and extend the creation time. If your business allows, create snapshots outside this peak period for faster uploads. Note The initial upload time may be long. Over time, as other uploads complete, each remaining snapshot can use more bandwidth. This increases the upload speed and reduces the estimated remaining time.
Billing	After you create snapshots, you are charged for snapshot storage based on the total size of your snapshots in each region. For more information, see Snapshot billing.
Other considerations	Do not change the state of the ECS instance (for example, by stopping or restarting it) while a snapshot is being created, or the creation process will fail. Data written to the cloud disk during snapshot creation is not included in the snapshot. You cannot resize a cloud disk while its snapshot is being created. To resize the disk, wait for the snapshot creation to complete. If a cloud disk is used to create a logical volume or a RAID array, use a snapshot consistency group and enable application-consistent snapshots to ensure data write-order and crash consistency. For more information, see snapshot consistency group. The following constraints apply to the creation of manual and automatic snapshots: ESSD series disks (ESSD, ESSD AutoPL, ESSD Entry, and ESSD zone-redundant disks) A single disk supports the concurrent creation of manual and automatic snapshots. However, the number of concurrent snapshots that can be created is limited. For more information, see Snapshot limits. If the number of concurrent snapshots that are being created for a disk reaches the upper limit, subsequent snapshot creation tasks fail. Previous generation disks (standard SSDs, ultra disks, and basic disks) Concurrent creation of manual and automatic snapshots is not supported. At the point in time when an automatic snapshot is scheduled to be created, if a snapshot (manual or automatic) is being created for the disk, the system does not create an automatic snapshot at this point in time. An automatic snapshot is created at the next scheduled point in time. If an automatic snapshot is being created for a disk, you must wait for the automatic snapshot to be created before you can manually create a snapshot. Note For more information about the differences between manual and automatic snapshots, see What are the differences between manual and automatic snapshots? After creation, a snapshot is automatically stored in a hidden Object Storage Service (OSS) bucket. You cannot select this bucket or view its data. For more information, see Snapshot storage locations.

Procedure

This section describes how to create a snapshot from the Snapshots page. Alternatively, you can create one from the Disks page.

Go to ECS console - Snapshots.
In the upper-left corner of the page, select a region and resource group.
On the Disk Snapshots tab, click Create Disk Snapshot.

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

Parameter		Description
Resource type		By default, Cloud Disk is selected to create a snapshot for a single cloud disk. Note You can also select Instance. Then, select one or more cloud disks from the instance to create a snapshot consistency group and create snapshots for multiple disks within the group. This ensures data consistency across the disks. For more information, see Create a snapshot consistency group.
Select Cloud Disk		Select the cloud disk for which you want to create a snapshot. This can be a system disk or a data disk.
Snapshot name		Enter a name for the snapshot.
Retention period		Set the retention period for the snapshot. You can choose to retain it permanently or specify a custom number of days. Retain permanently: After the snapshot quota is reached, you cannot create new snapshots. Custom retention period: The snapshot is automatically deleted after the specified retention period ends. Note For information about the quota for manual snapshots, see Snapshot overview. If you specify a custom retention period, the Retention Period column in the snapshot list displays the Released After xx Days message in highlighted text when only three days are left before the snapshot expires. You can extend the retention period before the snapshot expires. For more information, see Extend the retention period of a snapshot. Regardless of whether a snapshot is retained permanently or for a custom period, delete the snapshot when it is no longer needed to avoid incurring charges. For more information, see Delete a snapshot.
Advanced Configurations	Instant Access	The Instant Access feature is enabled by default for ESSD series disks (ESSD, ESSD AutoPL, ESSD Entry, and regional ESSD) and disabled by default for other types of cloud disks. Note The Instant Access feature makes snapshots available within seconds of being created. You can use a snapshot immediately for operations such as rolling back a cloud disk, creating a new cloud disk, or sharing the snapshot, without having to wait for the snapshot to be fully uploaded to OSS. For more information, see Snapshot Instant Access.
	Tags	Add key-value tags to the snapshot to help manage your resources.
	Resource Group	Assign the snapshot to a resource group to manage your resources by category.

(Optional) In the snapshot list, view the creation progress of the snapshot.

Snapshots are stored in OSS by default. To ensure the long-term security of your data and provide flexible recovery options, this OSS bucket is hidden.
- In the Progress column, view the progress of the snapshot upload to OSS. Hover over Progress of Upload to OSS: xx% to view the estimated remaining time.
  Note
  - The estimated remaining upload time is dynamic and changes based on several factors. For more information, see the Creation time description in the Considerations section.
  - You can call the DeleteSnapshot API operation to cancel a snapshot creation task that is in progress.
- When the Progress column shows Progress of Upload to OSS: 100%, the snapshot is successfully uploaded to OSS and the cloud disk data is backed up.