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Elastic Compute Service:Create a snapshot-consistent group

Last Updated:Oct 20, 2023

You can create a snapshot-consistent group to simultaneously take snapshots for multiple disks on one or more Elastic Compute Service (ECS) instances. If a business system spans multiple disks, you can create a snapshot-consistent group to ensure a consistent write order and crash consistency of business system data. This topic describes how to create a snapshot-consistent group.

Scenarios

Snapshot-consistent groups are suitable for the following scenarios:

  • A business system is deployed in a cluster file system that spans multiple ECS instances and requires point-in-time consistency and crash consistency across databases or enterprise-level applications. For example, a MySQL cluster is built on ECS instances, a logical volume in Logical Volume Manager (LVM) spans multiple volumes, or Oracle or SAP HANA clusters are migrated to the cloud.

  • Snapshots need to be created simultaneously for multiple nodes of a distributed application system, such as a large-scale website or a multi-application collaborative system.

  • Disks on multiple ECS instances that reside in the same region need to be backed up at the same time, and high point-in-time consistency is required.

Precautions

Before you use the snapshot-consistent group feature, take note of the following information:

  • When you create a snapshot-consistent group based on an ECS instance, take note of the following items:

    • To ensure that services are not affected, we recommend that you create the snapshot-consistent group during off-peak hours.

    • The ECS instance must be in the Running or Stopped state. Do not perform operations that change the instance status, such as stopping or restarting the instance. Otherwise, snapshots may fail to be created.

    • You can use the snapshot-consistent group feature to create snapshots only for enhanced SSDs (ESSDs) that are in the In Use state.

      • If ESSDs and disks of other categories are attached to the ECS instance, you can select only the ESSDs on the instance to create a snapshot-consistent group.

      • ESSDs that support the multi-attach feature do not support the snapshot-consistent group feature.

    • A single snapshot-consistent group can contain snapshots of up to 16 disks, including system disks and data disks, and cannot exceed 32 TiB in size.

    • The snapshots that you create are retained until you delete them. To reduce costs, we recommend that you delete unnecessary snapshots on a regular basis. For information about how to delete a snapshot, see Delete a snapshot.

  • For the amount of time that is required to create a snapshot-consistent group, take note of the following items:

    The amount of time that is required to create a snapshot-consistent group varies based on the sizes of the disks for which you want to create snapshots. The first snapshot of a disk is a full snapshot and takes an extended period of time to be created. Subsequent snapshots of the same disk are incremental snapshots and do not take the same amount of time as the first snapshot to be created. The amount of time required to create an incremental snapshot varies based on the amount of data that is changed since the previous snapshot.

Billing

You can use snapshot-consistent groups free of charge. Snapshots that belong to snapshot-consistent groups are billed based on the amount of storage space that is occupied by the snapshots. For more information, see Snapshots.

Scenario 1: Create a snapshot-consistent group based on a single ECS instance

If you want to back up and restore the data of an instance, you can create a snapshot-consistent group based on the instance.

  1. Log on to the ECS console.

  2. In the left-side navigation pane, choose Instances & Images > Instances.

  3. In the upper-left corner of the top navigation bar, select a region. 地域

  4. Find the instance based on which you want to create a snapshot-consistent group and choose 更多 > Disk and Image > Create Snapshot-consistent Group in the Actions column.

  5. In the Create Snapshot-consistent Group dialog box, configure the parameters that are described in the following table.

    Parameter

    Description

    Select cloud disk

    Select the ESSDs for which you want to create snapshots.

    Snapshot parameter settings

    Snapshot-consistent Group Name

    Enter a name for the snapshot-consistent group to facilitate management.

    Description

    Enter a description for the snapshot-consistent group to facilitate management.

    Tag

    Add tag key-value pairs to the snapshot-consistent group to facilitate management.

    Snapshot speed available

    • Enable Instant Access: You can select this check box to enable the instant access feature. By default, this check box is not selected.

    • Snapshot Speed Available Duration: If you select the check box, you can specify a validity period for the instant access feature. The default validity period is one day. The instant access feature is automatically disabled when the specified validity period ends.

    Note

    From 11:00 on October 12, 2023, canary release is performed by region to upgrade the instant access feature, and new snapshots of ESSDs at the performance levels 0, 1, 2, and 3 and ESSD AutoPL disks are instantly available after creation without the need for additional configurations. For more information, see Use the instant access feature.

    Application-consistent Snapshot

    Enable Application-consistent Snapshot: You can select this check box to enable the application-consistent snapshot feature. By default, this check box is not selected.

    You can use application-consistent snapshots for data rollback to prevent logs from being rolled back when applications such as databases start and to ensure that applications start in a consistent state. For more information, see Create application-consistent snapshots in the ECS console.

    Note

    The application-consistent snapshot feature is available in the following regions: China (Hong Kong), Singapore, China (Hangzhou), China (Shanghai), and China (Beijing).

  6. Click OK.

    After the snapshot-consistent group is created, you can choose Storage & Snapshots > Snapshots and click the Snapshot-consistent Groups tab to view the snapshot-consistent group.

Scenario 2: Create a snapshot-consistent group based on multiple ECS instances

If you want to back up and restore the data of multiple instances at the same time, you can create a snapshot-consistent group based on the instances.

  1. Log on to the ECS console.

  2. In the left-side navigation pane, choose Storage & Snapshots > Snapshots.

  3. In the upper-left corner of the top navigation bar, select a region.

    To create a snapshot-consistent group based on multiple instances, select the region in which the instances reside. For example, to create a snapshot-consistent group based on ECS instances that reside in the China (Hohhot) region, select China (Hohhot) from the drop-down list.

  4. Click the Snapshot-consistent Groups tab. Then, click Create Snapshot-consistent Group.

  5. On the Create Snapshot-consistent Group page, configure the parameters that are described in the following table.

    快照一致性组

    Parameter

    Description

    Data Source

    Select the instances based on which you want to create the snapshot-consistent group. You can search for instances only by instance ID. You can select one or more instances.

    Select cloud disk

    Select the ESSDs for which you want to create snapshots. Take note of the following items:

    • You can select only ESSDs.

    • You can select up to 16 disks, including system disks and data disks. The total size of the selected disks cannot exceed 32 TiB.

    Snapshot parameter settings

    Snapshot-consistent Group Name

    Enter a name for the snapshot-consistent group to facilitate management.

    Description

    Enter a description for the snapshot-consistent group to facilitate management.

    Tag

    Add tag key-value pairs to the snapshot-consistent group to facilitate management.

    Snapshot speed available

    • Enable Instant Access: You can select this check box to enable the instant access feature. By default, this check box is not selected.

    • Snapshot Speed Available Duration: If you select the check box, you can specify a validity period for the instant access feature. The default validity period is one day. The instant access feature is automatically disabled when the specified validity period ends.

    Note

    From 11:00 on October 12, 2023, canary release is performed by region to upgrade the instant access feature, and new snapshots of ESSDs at the performance levels 0, 1, 2, and 3 and ESSD AutoPL disks are instantly available after creation without the need for additional configurations. For more information, see Use the instant access feature.

What to do next

After you create a snapshot-consistent group, you can perform the following operations: