Backup Process of Direct Read Backups for Amazon

The backup operation includes the following stages:

1. For each instance, create an AMI.

   This operation creates crash-consistent snapshots of instance volumes.

2. Write the instance configuration file and instance metadata to the backup index.

3. Read the blocks from the snapshots and save the data to the storage media.

   When a call is made to the GetSnapshotBlock API, the API returns a checksum of the data block. On the access node, the checksum of the received block is calculated, and compared with the checksum returned by AWS. If the checksums are different, the received data is considered as corrupt. The received block is discarded and read again.

4. Retain the AMI and snapshots on Amazon for incremental backups.