Acronis Backup for Windows Server Essentials - User Guide - Manual (Page 229)

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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.
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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, de-duplication at incremental backup will not produce much
effect because:
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The deduplicated items that have not changed are not included in the incremental backup.
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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:
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The speed of access to the deduplication database
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The RAM capacity of the storage node
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The number of deduplicating vaults created on the storage node.
To increase deduplication performance, follow the recommendations below.
Place the deduplication database and deduplicating vault on separate physical
devices
To increase the speed of access to a deduplication database, the database and the vault must be
located on separate physical devices.
It is best to allocate dedicated devices for the vault and the database. If this is not possible, at least
do not place a vault or database on the same disk with the operating system. The reason is that the
operating system performs a large number of hard disk read/write operations, which significantly
slows down the deduplication.
Selecting a disk for a deduplication database
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The database must reside on a fixed drive. Please do not try to place the deduplication database
on external detachable drives.
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Minimal disk access time is important. The best hard drive choice is an enterprise-grade
Solid-State Drive (SSD), though using a fast IDE hard drive (7200 RPM or faster) or a SCSI drive is
acceptable.
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The volume to store the deduplication database should have at least 10 GB of free space. When
backing up a large number of machines, the required free space may exceed 10 GB.