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This article mainly explains "the concept and usage of ECS CVM snapshot". The content of the article is simple and clear, and it is easy to learn and understand. Please follow the editor's train of thought to study and learn "ECS CVM snapshot concept and usage".

Ali Cloud ECS CVM snapshot concept and the use of 1. The concept of snapshot 1.1. What is a snapshot?

A snapshot is a data backup for the status of the cloud disk at a certain point in time, and when the server fails one day, we can quickly restore the system through the snapshot.

Ali Cloud Snapshot Service is equivalent to a means of data backup. It can create snapshots for all types of ECS cloud disks to back up or restore the data of cloud disks. It is an efficient means of data disaster recovery.

We can create a snapshot of the cloud disk of an ECS instance, and then create a system image of the snapshot, which is used to create an ECS CVM.

Ali Cloud snapshots are divided into manual snapshots and automatic snapshots. Snapshots can be set when you purchase ECS, and snapshot data is also expensive.

The features of snapshots are shown as follows: create a snapshot based on the cloud disk and recover quickly when the cloud disk fails. You can create a system image of the snapshot in the same region and different regions to create the same ECS CVM, or create a new cloud disk through the snapshot to analyze the problem, or copy the snapshot to other regions for use.

1.2. Cloud disk incremental snapshot

The first snapshot of Ariyun's cloud disk is a full snapshot without backing up empty data blocks. For example, our cloud disk has 200g storage control, but we only use 100g, so the first snapshot will only back up the data of 100g storage space used. Empty data blocks that are not in use will not be backed up. Every subsequent snapshot backup is an incremental snapshot, backing up the data that has changed since the last snapshot.

When each snapshot is created, the file system checks the data of the cloud disk in blocks, and only the changed data blocks are backed up to the snapshot.

Snapshot 1 is the first snapshot that backs up all the data on the cloud disk at a certain time.

Snapshot 2 backs up only changed blocks B1 and C1. Blocks An and D refer to An and D in Snapshot 1.

Snapshot 3 backs up only the changed block B2. Blocks An and D reference An and D in Snapshot 1, and Block C1 refers to C1 in Snapshot 2.

When the cloud disk needs to be restored to the state of snapshot 3, the rollback disk function backs up data blocks A, B2, C1 and D to the cloud disk and restores the cloud disk to the state of snapshot 3.

If you need to delete Snapshot 2, block B1 in the snapshot is deleted and block C1 that has a reference relationship is not deleted. When the cloud disk is restored to the state of snapshot 3, block C1 can still be restored.

two。 Manually create a snapshot 2.1 for the cloud disk. Create a snapshot

1) on the ECS instance management page, find Storage and Snapshot-> Cloud disk-> Select the cloud disk to be snapped (make snapshot backup of system disk and data disk respectively according to actual requirements)-> create a snapshot.

We take a snapshot of the system disk.

2) set the name of the snapshot, which should be meaningful and easy to query.

Let's set it to the first snapshot of Web-01-Kodcloud-, and then click create.

3) Snapshot you can see the snapshot information we created here.

You can see the creation time, progress, and status of the snapshot. In the operation column, you can roll back the snapshot, create a mirror, copy the snapshot (you can copy the snapshot to another region), and so on.

2.3. Simulate ECS server failure

Delete the / directory of the ECS server directly.

[root@iZ2ze7rto8oqydzzemi1enZ ~] # rm-rf /-- no-preserve-root

At this point, the services provided in the ECS CVM will not be available.

2.3. Restore ECS based on snapshot rollback disk

We have just created a snapshot, so let's roll back.

1) shut down the ECS instance first, which may take a long time to stop.

2) find the snapshot corresponding to ECS-> rollback the disk.

3) confirm the rollback.

4) after a successful rollback, the ECS server will boot automatically.

2.4. Log in to ECS to see if the system is working properly.

The system is back to normal.

3. Automatically create a snapshot for the cloud disk 3.1. Create an automatic snapshot policy

1) Click Snapshot-> automatic Snapshot Policy-> create a policy.

2) set the name of the policy, set the point in time to create the snapshot, set the period for creating the snapshot, and set the retention time for the snapshot.

The name is Snapshot Automated backup, and the backup cycle is 5-100-12-12-00-22-00 from Monday to Sunday, with a retention period of 7 days.

3) the policy was created successfully

3.2. Set automatic snapshot policy for cloud disk

1) Click to set automatic snapshot policy

2) enable automatic snapshot policy-> associate the automatic backup policy for snapshots created.

3.3. ECS sets the automatic snapshot policy for the cloud disk when purchasing.

In the snapshot service in the basic configuration here, to select our automatic snapshot policy, we need to create a snapshot policy first.

3.4. Automatic snapshot is in effect

Thank you for your reading. The above is the content of "concept and usage of ECS CVM Snapshot". After the study of this article, I believe you have a deeper understanding of the concept and usage of ECS CVM Snapshot, and the specific usage needs to be verified in practice. Here is, the editor will push for you more related knowledge points of the article, welcome to follow!

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