How to retain disk data status at a certain point in time - snapshot

Based on the introduction, this article focuses on how to retain the disk data status at a certain point in time, focusing on the specific steps to create a snapshot.

Create a snapshot

Snapshots can retain the disk data status at a certain point in time and are often used for data backup and custom mirroring.

Usage scenarios

Creating a snapshot is an extremely important operation. In scenarios with operational risks, you can create snapshots in advance to back up data. For example, modifying key system files, migrating instances from a classic network to a private network VPC, daily data backup, preventing network attacks, replacing operating systems, providing data support for certain production environments, and other scenarios with operational risks.

Snapshots can also create custom images to quickly deploy application environments in a large number of ECS instances.

Notes

Description

Starting from March 28, 2017, ECS snapshots have been officially commercialized and included in charges For service and billing details, please refer to Snapshot Billing. For more information about snapshot charges, please refer to the Snapshot Commercialization FAQ.

Creating a snapshot may slightly reduce disk performance, and I/O performance may temporarily slow down. You need to avoid business peaks.

Snapshots will only back up data at a certain moment. During the creation of the snapshot, the incremental data generated by operating the disk will not be synchronized to the snapshot.

To ensure that the snapshot is created successfully, you cannot modify the status of the ECS instance, such as stopping or restarting the ECS instance, when creating the snapshot.

When creating a snapshot based on an instance, the instance must be running or stopped.

When creating a snapshot from a disk, the disk must be in use.

The snapshots you create will be retained forever. Please delete snapshots that are no longer needed regularly to avoid continuous deduction of snapshot capacity.

If you use a single disk with multiple partitions to create an extended volume, the created snapshot can roll back the disk normally.

After using multiple disks to create a dynamically extended volume, when there is no I/O operation on the data in the extended volume, the created snapshot can roll back the disk normally. If there are always I/O operations in the extended volume, the data integrity of the rolled-back disk cannot be guaranteed.

Operation steps

The steps to create a snapshot on the ECS management console are as follows:

Log in to the ECS management console.

Select a region.

In the left navigation bar, click Instances.

Find the instance that needs to create a snapshot and click Manage.

Click the instance disk on the left, and then click Create Snapshot on the right of the corresponding disk. Only one disk can be selected at a time, and the disk attributes can be system disk or data disk.

Enter the name of the snapshot and click OK.

Click the snapshot of this instance on the left to view the snapshot tasks. You can see the snapshot progress, estimated time remaining, and snapshot status.

You can also use the ECS API CreateSnapshot to create a snapshot.

Time required

The time required to create a snapshot mainly depends on the disk capacity.

According to the incremental principle of snapshots, the first snapshot of the disk is a full snapshot, which takes a long time. Creating a snapshot again takes a relatively short time, but it still depends on the amount of data changes between the previous snapshot. The bigger the change, the longer it takes.

Next step

After creating the snapshot, you can continue with the following operations:

Roll back the cloud disk

Create a cloud disk using a snapshot

Create a custom image using a snapshot

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