Configuring throttling for backup storage

When the percentage of used space on underlying storage reaches a certain threshold, backup storage starts to throttle write operations to slow down the data flow. With the public cloud destination, however, this threshold applies to the local storage usage as backup storage uses the local storage as the staging area.

By default, the throttling starting value is 85%. Throttling intensity increases with space consumption, until the percentage of free storage space is half the difference between the total storage space and the throttling starting value. After that, throttling works with maximum intensity until more storage space is added. For example, if the starting value is 85%, throttling maximum intensity will be reached when the storage has (100%-85%)/2 of free space left, that is, 7.5%. The throttling starting value can be increased up to 95%.

When working with public clouds, backup storage throttling may also start for certain backup archives even if there is still enough free space left on the local storage. This happens when the size occupied by a single backup archive in the staging area is greater than or equal to the per-archive threshold. By default, this threshold is set to 300 MiB, which is a recommended value for small clusters below 500 GiB in size. If your cluster has more storage space, you can increase the throttling starting value per archive:

For medium clusters with 500 GiB to 1 TiB of available space, it is recommended to set a value of 1 to 3 GiB, depending on the number of files on the storage.
For large clusters above 1 TiB in size, the throttling starting value can be changed up to 100 GiB.

To monitor backup storage throttling, go to Storage services > Backup storage > Overview and check the Append throttling chart.

Prerequisites

The backup storage cluster is created and registered in the Cloud Management Panel, as described in Provisioning backup storage space.

To change the throttling starting value

Admin panel

On the Storage services > Backup storage screen, go to the Settings tab, and then click Throttling configuration.
Select the desired throttling starting value for local storage.
[For backup storage with the public cloud destination] Select the desired throttling starting value per archive.
Click Save.

Command-line interface

Use the following command:

vinfra service backup throttling set [--soft-threshold <soft_threshold>]
                                     [--s3-threshold <s3_threshold>]

--soft-threshold <soft_threshold>: Soft threshold limit, in percent. The valid range is 85-95%.
--s3-threshold <s3_threshold>: Object storage threshold limit, in MiB. Must be greater than the default limit of 300 MiB. This parameter can only be used for backup storage with the public cloud destination.

For example, to change the throttling starting value to 90%, run:

# vinfra service backup throttling set --soft-threshold 90

The updated parameters will be shown in the vinfra service backup throttling show output:

# vinfra service backup throttling show
+----------------+-------+
| Field          | Value |
+----------------+-------+
| soft_threshold | 90    |
+----------------+-------+

To reset the throttling starting value to default

Admin panel

On the Storage services > Backup storage screen, go to the Settings tab, and then click Throttling configuration.
Click Reset to default.
In the confirmation window, click Reset.

Command-line interface

Use the following command:

vinfra service backup throttling reset

For example, to reset the throttling starting value to 85%, run:

# vinfra service backup throttling reset

The updated parameters will be shown in the vinfra service backup throttling show output:

# vinfra service backup throttling show
+----------------+-------+
| Field          | Value |
+----------------+-------+
| soft_threshold | 85    |
+----------------+-------+