Elastic Compute Service (ECS) Snapshot is an agentless data backup service that allows you to create a snapshot which captures the point-in-time state of a disk or a disk group to back up data. To improve fault tolerance and ensure data security, we recommend that you create snapshots to back up data before you perform important operations, such as rolling back disks, modifying critical system files, and replacing operating systems. This topic describes how to create a snapshot for a disk.
Prerequisites
ECS Snapshot is activated. For more information, see Activate ECS Snapshot.
The disk for which you want to create a snapshot is in the In Use or Unattached state. Take note of the following items:
If the 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 disk is in the Unattached state, make sure that the disk was attached to an ECS instance at least once. Snapshots cannot be created for cloud disks that have never been attached to an ECS instance.
Precautions
When you create a snapshot, take note of the following items:
Do not perform operations that change the status of the associated ECS instance, such as stopping or restarting the instance. Otherwise, snapshot creation fails.
You are charged for snapshots. For more information, see Snapshots.
NoteThe snapshots that you created are stored indefinitely until you delete the snapshots. We recommend that you delete the snapshots that you no longer need on a regular basis to prevent unnecessary snapshot storage fees. For more information, see Delete a snapshot.
We recommend that you create snapshots during off-peak hours because snapshot creation degrades the I/O performance of disks by up to 10% and slows down data reads and writes.
If operations are performed on the disk and incremental data is generated when a snapshot is being created, the incremental data is not included in the snapshot.
If you create an extended volume from a single multi-partition disk, the snapshot that you created can be used to roll back the disk.
When you use a disk to create a dynamic extended volume or a RAID array, we recommend that you create a snapshot-consistent group and enable the application-consistent snapshot feature. When a business system involves multiple disks, you can create a snapshot-consistent group to ensure a consistent write order and the crash consistency of business system data. For more information, see Create a snapshot-consistent group and Create application-consistent snapshots in the ECS console.
Procedure
This section describes how to create a snapshot for a disk on the Snapshots page in the ECS console. You can also go to the Disks page by choosing Storage & Snapshots > Disks in the left-side navigation pane of the ECS console and create a snapshot for a disk on the Disks page.
Log on to the ECS console.
In the left-side navigation pane, choose .
In the top navigation bar, select the region and resource group to which the resource belongs.
On the Disk Snapshots tab, click Create Disk Snapshot.
In the Create Disk Snapshot dialog box, configure parameters. The following table describes the parameters.
Parameter
Description
Disk
The disk for which you want to create a snapshot.
Snapshot Name
The name of the snapshot.
Snapshot Type
The type of the snapshot. Valid values: Normal Snapshot and IA Snapshot.
Normal Snapshot: creates a normal snapshot. Several minutes are required to create the snapshot. The amount of time that is required to create a normal snapshot for a disk varies based on the size of the snapshot. The first time you create a normal snapshot for the selected disk, the process requires a long period of time to complete.
IA Snapshot: creates an instance access (IA) snapshot. You can create IA snapshots only for enhanced SSDs (ESSDs) at the performance levels 0, 1, 2, and 3 (PL0, PL1, PL2, and PL3 ESSDs) and ESSD AutoPL disks. For more information, see Use the instant access feature.
After you create snapshots, you are charged snapshot storage fees per region based on the total size of the snapshots that are stored in the region. For information about the billing rules of snapshots, see Snapshots.
Retention Period
The number of days for which the snapshot is retained. Valid values: Permanently and Retained For. After the retention period of the snapshot ends, the system automatically deletes the snapshot.
NoteIf the snapshot is about to be released within three days, Released After {days} Days is displayed in the Retention Period column corresponding to the snapshot.
If you set the Retention Period parameter to Retained For and the snapshot is created, find the snapshot in the snapshot list and click the
icon in the Retention Period column or choose 
> Extend Retention Period in the Actions column to extend the retention period of the snapshot based on your business requirements.
Tag
The tag that you want to add to the snapshot. You can use tags to classify snapshots to facilitate search and batch operations.
Resource Group
The resource group to which you want to assign the snapshot. You can use resource groups to manage snapshots at different levels.
Click OK.
(Optional) View the progress of creating the snapshot on the Disk Snapshots tab.
After you create the snapshot, the snapshot is stored in an Object Storage Service (OSS) bucket that is managed by ECS Snapshot.
View the progress of uploading the snapshot to OSS in the Progress column. When you move your pointer over Progress of Upload to OSS: xx%, the estimated remaining amount of time that is required to upload the snapshot is displayed.
NoteThe estimated remaining amount of time that is required to upload a snapshot to OSS dynamically varies in real time based on multiple factors, including the size of the snapshot and the number and size of snapshots that are being created by other users.
A longer period of time is required to upload a larger snapshot to OSS.
The peak periods of creating automatic snapshots are during the early morning. The number and size of snapshots that are uploaded increases during the peak periods, and the bandwidth that is allocated to each snapshot may decrease. The initial estimated amount of time that is required to upload each snapshot may increase. The number of snapshots that are being uploaded decreases over time. In this case, more bandwidth can be allocated to each snapshot, the transfer speed increases, and the estimated remaining amount of time that is required to upload each snapshot is reduced. To achieve higher upload speeds, we recommend that you do not create manual snapshots during the peak periods.
If Progress of Upload to OSS: 100% is displayed, the snapshot is uploaded to OSS.