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Backup Copying Process

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    The backup copy job copies VM data per VM at the block level. That is, the backup copy job does not copy the whole VBK, VIB or VRB file from the source backup repository to the target backup repository. Instead, it works with data of separate VMs stored in these files.

    When the backup copying process starts, Veeam Backup & Replication accesses VM backup files in the source backup repository, retrieves data blocks for a specific VM from the backup file, copies them to the target backup repository and composes copied blocks into a backup file in the target backup repository. Therefore, the backup copying process does not affect virtual infrastructure resources, does not require an additional snapshot of a VM and does not produce any load on VMs whose backups are copied.

    In the target backup repository, the backup copy job creates a chain of restore points using the incremental backup method. The target backup repository always contains only one active incremental backup chain. Restore points in the chain are rotated according to the specified retention policy. For more information, see Retention Policy for Backup Copy Jobs.

    The backup chain on the target backup repository is created in the following manner:

    1. The first synchronization interval of the backup copy job always produces a full backup file. The full backup file is created in the following way:
    1. From the backup chain on the source backup repository, Veeam Backup & Replication copies data blocks that are necessary to build a full backup of a VM as of the most recent state. Data blocks can be copied from one or several backup files in the chain. If the backup chain on the source backup repository was created using the reverse incremental backup method, Veeam Backup & Replication simply copies data blocks of the latest full backup.

    Backup Copying Process 

    If the backup chain on the source backup repository was created using the forward incremental backup method, Veeam Backup & Replication copies data blocks from the first full backup and a set of incremental backups to form a full backup of a VM as of the most recent state.

    Backup Copying Process
     

    1. On the target backup repository, Veeam Backup & Replication writes all copied data blocks to the same full backup file.
    1. At every next synchronization interval, when a new restore point appears on the source backup repository, Veeam Backup & Replication copies incremental changes from this most recent restore point and transfers them to the target backup repository. On the target backup repository, Veeam Backup & Replication writes the copied data blocks to the incremental backup file.

    Backup Copying Process 

    The backup copy job can be created for one VM or several VMs. If the backup copy job is created for several VMs, you can define the order in which the VMs should be processed.

    By default, backup copy jobs process VMs in the job in parallel, starting from the first VM in the order list. If any VM cannot be processed for some reason, for example, in case a new restore point for this VM is not available yet, the job will start processing the next VM. Once this VM is processed, the job will attempt to copy the unprocessed VM once again.

    Backup Copying Process Note:

    Backup copy jobs process VMs in parallel only if you transport VM data over the direct data path. If you use WAN accelerators for backup copy jobs, VMs will be processed sequentially. For more information, see Data Transport Path.

    Parallel data processing over the direct data path is enabled by default. If necessary, you can disable parallel data processing using a registry key. For more information, contact the Veeam Support Team.

    If you do not enable the Use per-VM backup files option for the target backup repository, Veeam Backup & Replication creates one backup file on the target backup repository and stores to it data for all VMs processed by the job. If the Use per-VM backup files option is enabled, data of every VM in the job is stored to separate backup files on the target backup repository.

    To minimize the amount of traffic going over the network, Veeam Backup & Replication uses the data compression and deduplication technologies. For more information, see Compression and Deduplication.

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