ACRONIS Backup & Recovery 11 Guía de usuario descargar pdf (Pagina 205)

deduplicating vault. The Deduplication add-on to the agent must be installed on any machine that

backs up to such vault. Without the add-on backing up to the vault is not possible.

The deduplication is performed on data blocks. The block size is 4 KB for disk-level backups and 1 B

to 256 KB for file-level backups. Each file that is less than 256 KB is considered a data block. Files

larger than 256 KB are split into 256-KB blocks.

Acronis Backup & Recovery 11 performs deduplication in two steps:

Deduplication at source

Performed on a managed machine during backup. The agent uses the storage node to determine

what data can be deduplicated and does not transfer the data blocks whose duplicates are

already present in the vault.

Deduplication at target

Performed in the vault after a backup is completed. The storage node analyses the vault's

contents and deduplicates data in the vault.

When creating a backup plan, you have the option to turn off deduplication at source for that plan.

This may lead to faster backups but a greater load on the network and storage node.

Deduplication database

Acronis Backup & Recovery 11 Storage Node managing a deduplicating vault, maintains the

deduplication database, which contains the hash values of all data blocks stored in the vaultexcept

for those that cannot be deduplicated, such as encrypted files.

The deduplication database is stored in the storage node local folder. You can specify the database

path when creating the vault.

The size of the deduplication database is about 1.5 percent of the total size of unique data stored in

the vault. In other words, each terabyte of new (non-duplicate) data adds about 15 GB to the

database.

If the database is corrupted or the storage node is lost, while the vault retains its contents, the new

storage node rescans the vault and re-creates the vault database and then the deduplication

database.

6.4.7.2 How deduplication works

Deduplication at source

When performing a backup to a deduplicating vault, Acronis Backup & Recovery 11 Agent calculates

a fingerprint of each data block. Such a fingerprint is often called a hash value.

Before sending the data block to the vault, the agent queries the deduplication database to

determine whether the block's hash value is the same as that of an already stored block. If so, the

agent sends only the hash value; otherwise, it sends the block itself. The storage node saves the

received data blocks in a temporary file.

Some data, such as encrypted files or disk blocks of a non-standard size, cannot be deduplicated. The

agent always transfers such data to the vault without calculating the hash values. For more

information about restrictions of deduplication, see Deduplication restrictions (p. 209).

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ACRONIS Backup & Recovery 11 Guía de usuario Pagina 205