Why is AWS Backup unable to back up my FSx for ONTAP volume?

Short description

If there's insufficient space remaining on the file system, then backups commonly fail. Even if you have available space on the volume, the volume is thinly provisioned. This means that the volume only consumes storage capacity from your file system for the data that's stored in the volume. Even if you have available space on the volume, you might not have available space on the file system SSD (aggregate : aggr1).

Before creating a backup of an FSx for ONTAP volume, Amazon FSx first verifies that the volume isn't full. You can't back up full volumes because FSx for ONTAP requires a small amount of free space to create a snapshot. If a volume utilization is above its fullness threshold, then FSx for ONTAP considers a volume full. By default, the fullness threshold is 98%.

Also, when reporting a volume's free space, FSx for ONTAP considers the available capacity that's smaller, either the volume's or the file system's SSD tier.

For example, you create a 100-TB volume on a 1-TB SSD file system. FSx for ONTAP reports that volume with 1 TB of free capacity and 99% full. 99% exceeds the volume's default fullness threshold of 98%. The backup of your volume might fail because your volume is reporting that it's more than 98% full.

Resolution

Run the describe-backups AWS Command Line Interface (AWS CLI) command to view any failure messages for the backup. In the following example command, replace xyzabc with the ID of your backup.

$ aws fsx describe-backups --backup-id backup-xyzabc --region region\_id

Note: If you receive errors when running AWS CLI commands, make sure that you're using the most recent version of the AWS CLI.

Note: The backup that AWS Backup creates is stored in the .snapshot directory on the volume itself. This means that the backup consumes space on the volume.

Increase the space-full-threshold-percent to 100%

FSx for ONTAP volumes are thinly provisioned. So, you can provision a volume with more size than the file system. This might cause space issues when creating snapshots. For example, if you create a 100-TB volume in a 1-TB file system, you can use NetApp ONTAP CLI to create snapshots. But, you can't create snapshots with AWS Backup. For a 1-TB file system, you can create backups of a volume that's about 42 TB. Any additional TB in size to the volume causes AWS Backup to fail to create a backup.

To correct this, run the following NetApp ONTAP CLI command:

::> vol modify -vserver <svm\_name> -volume <vol\_name> -space-full-threshold-percent 100

The preceding command increases the full threshold of your volume. This prevents FSx for ONTAP from reporting your volume as full, allowing backups to proceed.

Increase the file system's SSD storage capacity

Increase your file system's SSD storage capacity so that free SSD capacity is always at least 2% larger than the size of your largest volume. For example, if your largest volume is 100 TB in size, size your SSD capacity to always have at least 2 TB of free capacity. By doing this, even if you keep your volumes' space-full-threshold-percent at the default value of 98%, FSx for ONTAP doesn't report your volumes as full.

Check the snapshot autodelete initiation setting on the volume

If your volume has snapshot autodelete (from the NetApp website) turned on with the initiation set as snap_reserve, then your backup might fail. The snap_reserve parameter deletes snapshots when the space reserved for the snapshots reaches the value assigned in Space Reserved for Snapshot Copies (from the NetApp website). The default value is 5%. When a backup is created, Amazon FSx takes a snapshot of the volume, then compares this snapshot to the previous backup snapshot, if one exists. Amazon FSx then copies only the changed data into the backup. When a previous snapshot has a larger size than the value that's assigned in Space Reserved for Snapshot Copies, the new backup automatically deletes at creation. This means that Amazon FSx can't create backups of the volume.

To avoid this, increase the size of the volume so that the Space Reserved for Snapshot Copies parameter exceeds the size of the previous backup. To set the snapshot reserve to a value larger than the size of the previous backup, run the following NetApp ONTAP CLI command:

::> volume modify -vserver com -volume vol\_name -percent-snapshot -space 20

The preceding command sets the Space Reserved for Snapshot Copies option to 20%. For more information, see Manage the Snapshot copy reserve NetApp documentation.

Related information

Working with backups

Working with snapshots

You have insufficient volume capacity