Quantum DXi4700 User Manual page 124

Chapter 6: Replication
Replication
Replication
Replication occurs when replication is enabled for a deduplicated NAS share or VTL partition and a
replication schedule is configured (or manual replication is performed on a regular basis). For replication to
occur, the source system must be configured to point to the target system. Similarly, the target system must
be configured to accept data from the source system.
To optimize the replication process, deduplicated data is continuously sent in the background from the
source system to the target system. However, a snapshot that preserves the file structure of your data is
sent to the target system only when a scheduled or manual replication job occurs. A snapshot contains all of
the information that is necessary to recreate a share or partition just as it was at the point in time when the
snapshot was created.
Caution: A saved snapshot is necessary to recover your data at a later time. For this reason, it is not
enough to simply enable replication for a share or partition. You must also configure a replication
schedule (recommended) or perform manual replication on a regular basis to send snapshots of the
share or partition to the target system.
If the source system ever becomes unavailable, you can recover the share or partition on the target system
using a saved snapshot. After you recover a share or partition, it is recreated on the target system and is
available for use. Once the source system becomes available again, you can perform a failback operation to
restore the share or partition to its original location.
Directory/File or Cartridge Based Replication
Like replication, Directory/File or Cartridge Based Replication sends data from a NAS share or VTL partition
to another system where it can be accessed. However, Directory/File or Cartridge Based Replication differs
in a number of important ways:
Both replication and Directory/File or Cartridge Based Replication must be enabled for the share or
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partition.
A unique Sync ID is used to associate the replicated share or partition on the source system with the
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share or partition that will receive the replicated data on the target system.
You do not need to schedule or manually perform share or partition through the remote management
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console. Instead, replication is triggered when a file is closed or a period of time after it is modified (NAS
shares), or when a tape cartridge is unmounted (VTL partitions).
Additional Information
For CIFS/SMB shares, a file is replicated immediately after it is closed. For NFS shares, a file is
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replicated after it has been idle (not accessed) for several minutes.
To optimize the replication process, deduplicated data is continuously sent in the background from
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the source system to the target system. Any remaining data is sent (along with metadata) at the
time a file is closed or a tape cartridge is unmounted.
Quantum DXi4700 User's Guide 124