Changing the redundancy scheme for backup storage

You can update the redundancy scheme used for backup storage by changing the storage policy. Such a configurable redundancy scheme ensures high scalability and maximum efficiency of backup storage.

During the re-encoding process, data is partially stored with a new redundancy scheme, and the other part is stored with an old scheme. However, the system uses the storage policy with the least redundancy. For example, if you are switching from the 1+0 encoding mode to 1+2, the system will use the 1+0 encoding mode. In this case, it is critical not to turn off any storage node or disk until the process is complete.

Note that the reported size of backup archives and their space usage in Acronis Cyber Protect Cloud change during and after the re-encoding process. During re-encoding, the size of backup archives increases for a short period of time. At some point, it may reach 120% of the initial size. After re-encoding, the reported size of backup archives and their space usage are usually lower than the initial values. This happens due to distribution optimization of storage chunks that is performed in addition to physical chunks optimization. The average difference between the initial backup size and its size after re-encoding is 10%.

If you changed the encoding scheme for your backup storage cluster with the help of the technical support team, re-apply your redundancy settings in the admin panel to ensure that all data was encoded.

Limitations

Redundancy by replication is not supported for backup storage.

Prerequisites

A clear understanding of the concept Storage policies.
The backup storage cluster is created and registered in the Cloud Management Panel, as described in Provisioning backup storage space.

To change the storage policy

Admin panel

On the Storage services > Backup storage screen, go to the Settings tab, and then click Storage policy.
Select the desired storage tier, failure domain, or data redundancy mode.
Click Save.

When the re-encoding process starts, its progress and the estimated time of completion will be shown on the screen. During this process, you can select another redundancy scheme. In this case, the current re-encoding process will be stopped and the new redundancy scheme will be applied.

Command-line interface

Use the following command:

vinfra service backup volume-params change [--tier {0,1,2,3}]
                                           [--encoding <M>+<N>]
                                           [--failure-domain {disk,host,rack,row,room}]

--tier {0,1,2,3}

Storage tier

--encoding <M>+<N>

Storage erasure encoding mapping in the format:

M: number of data blocks
N: number of parity blocks

--failure-domain {0,1,2,3,4}

Storage failure domain

For example, to change the storage tier to 0, the erasure coding scheme to 1+2, and the failure domain to host, run:

# vinfra service backup volume-params change --tier 0 --encoding 1+2 \
--failure-domain host

The updated parameters will be shown in the vinfra service backup volume-params show output:

# vinfra service backup volume-params show
+----------------+-------------+
| Field          | Value       |
+----------------+-------------+
| failure_domain | host        |
| redundancy     | m: 1        |
|                | n: 2        |
|                | type: raid6 |
| tier           | 0           |
+----------------+-------------+