File replication and object replication

Replication and Disaster Recovery Administration Guide for Hitachi NAS Platform

Part Number

There are two basic methods used to replicate file system contents (data and metadata): file-level replication and object-level replication.

  • File-level replication operates by copying file system structures, such as files, directories, and the metadata for those structures.

    In file-based replication operations, to determine which files or directories to replicate, the metadata for the files and directories must be retrieved (often from disk) and examined, a process that is resource intensive.

  • Object-level replication operates by copying the objects that make up the files, directories, and metadata for the files and directories in the file system. Object replication replicates these objects natively, regardless of which file or directory that they may belong to, negating the need to assemble all of the objects associated with a file or directory before transfer, making the overall transfer more efficient.
    Note: Object replication operates only on file systems, not on individual directories or files.

    Both replication methods can be used with policies and schedules to automate data replication based on criteria you specify, and both replication methods can be initiated and managed manually, through the NAS Manager or the CLI.

    A Replication license is required to use either file replication or object replication, and a single Replication license enables both features.

    Care should be taken when configuring systems with a single migration destination for both replication source and target (known as a triangular arrangement). Such arrangements should not be considered a valid solution in any disaster recovery (DR) or backup scenario, as there is only a single copy of the user data pointed to by XVLs at each end of the replication policy.