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Compacting
After one or more backups or archives have been deleted from the vault—either manually or during
cleanup—the data store may contain blocks which are no longer referred to from any archive. Such
blocks are deleted by the compacting task, which is a scheduled task performed by the storage node.
By default, the compacting task runs every Sunday night at 03:00. You can re-schedule the task by
selecting the corresponding storage node, clicking View details (p. 224), and then clicking
Compacting schedule. You can also manually start or stop the task on that tab.
Because deletion of unused blocks is resource-consuming, the compacting task performs it only
when a sufficient amount of data to delete has accumulated. The threshold is determined by the
Compacting Trigger Threshold (p. 225) configuration parameter.
7.5.7.3 When deduplication is most effective
The following are cases when deduplication produces the maximum effect:
When backing up in the full backup mode similar data from different sources. Such is the case
when you back up operating systems and applications deployed from a single source over the
network.
When performing incremental backups of similar data from different sources, provided that the
changes to the data are also similar. Such is the case when you deploy updates to these systems
and apply the incremental backup.
When performing incremental backups of data that does not change itself, but changes its
location. Such is the case when multiple pieces of data circulate over the network or within one
system. Each time a piece of data moves, it is included in the incremental backup which becomes
sizeable while it does not contain new data. Deduplication helps to solve the problem: each time
an item appears in a new place, a reference to the item is saved instead of the item itself.
Deduplication and incremental backups
In case of random changes to the data, deduplication at incremental backup will not produce much
effect because:
The deduplicated items that have not changed are not included in the incremental backup.
The deduplicated items that have changed are not identical anymore and therefore will not be
deduplicated.
Deduplication and database backups
Deduplication is not very effective for backing up a database on a regular basis. This is because
changes to the database are usually unique and, therefore, cannot be deduplicated. We recommend
backing up databases to a non-deduplicating vault.
7.5.7.4 Deduplication best practices
Deduplication is a complex process that depends on many factors.
The most important factors that influence deduplication speed are:
The speed of access to the deduplication database
The RAM capacity of the storage node
The number of deduplicating vaults created on the storage node.
To increase deduplication performance, follow the recommendations below.
