ACRONIS Backup & Recovery 10 Advanced Server User's Guide download pdf (Page 72)

 Indexing of a backup requires that the vault have free space with a minimum size of 1.1

multiplied by the size of the archive the backup belongs to. If there is not enough free space in

the vault, the indexing task will fail and start again after 5–10 minutes, on the assumption that

some space has been freed up as a result of cleanup or of other indexing tasks. The more free

space there is in the vault, the faster your archives will reduce to the minimum possible size.

 When backing up multiple systems with similar content, back up one of the similar systems first,

so that Acronis Backup & Recovery 10 Storage Node indexes all the system's files as potential

deduplication items. This will lead to faster backup processes and less network traffic (because of

effective deduplication at source), regardless of whether the backups are performed

simultaneously or not.

Before starting the subsequent backups, make sure that the indexing task has finished

deduplication of the first backup and is now idle. You can view the state of the indexing task in

the list of tasks on Acronis Backup & Recovery 10 Management Server.

Deduplication ratio

The deduplication ratio shows the size of archives in a deduplicating vault in relation to the size they

would occupy in a non-deduplicating vault.

For example, suppose that you are backing up two files with identical content from two machines. If

the size of each file is one gigabyte, then the size of the backups in a non-deduplicating vault will be

approximately 2 GB, but this size will be just about 1 GB in a deduplicating vault. This gives a

deduplication ratio of 2:1, or 50%.

Conversely, if the two files had different content, the backup sizes in non-deduplicating and

duplicating vaults would be the same (2 GB), and the deduplication ratio would be 1:1, or 100%.

What ratio to expect

Although, in some situations, the deduplication ratio may be very high (in the previous example,

increasing the number of machines would lead to ratios of 3:1, 4:1, etc.), a reasonable expectation

for a typical environment is a ratio between 1.2:1 and 1.6:1.

As a more realistic example, suppose that you are performing a file-level or disk-level backup of two

machines with similar disks. On each machine, the files common to all the machines occupy 50% of

disk space (say, 1 GB); the files that are specific to each machine occupy the other 50% (another

1 GB).

In a deduplicating vault, the size of the first machine's backup in this case will be 2 GB, and that of

the second machine will be 1 GB. In a non-deduplicating vault, the backups would occupy 4 GB in

total. As a result, the deduplication ratio is 4:3, or about 1.33:1.

Similarly, in case of three machines, the ratio becomes 1.5:1; for four machines, it is 1.6:1. It

approaches 2:1 as more such machines are backed up to the same vault. This means that you can

buy, say, a 10-TB storage device instead of a 20-TB one.

The actual amount of capacity reduction is influenced by numerous factors such as the type of data

that is being backed up, the frequency of the backup, and the backups' retention period.

Deduplication restrictions

Block-level deduplication restrictions

During a disk backup to an archive in a deduplicating vault, deduplication of a volume's disk blocks is

not performed in the following cases:

1 2 ... 67 68 69 70 71 72 73 74 75 76 77 ... 380 381

No comments

ACRONIS Backup & Recovery 10 Advanced Server User's Guide Page 72