HP StorageWorks P2000 HP StorageWorks P2000 G3 MSA System SMU Reference Guide - Page 102

which uniquely identifies that the data in those snapshots are

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Figure 4 Intersite and intrasite replication sets Remote replication uses snapshot functionality to track the data to be replicated and to determine the differences in data updated on the master volume, minimizing the amount of data to be transferred. Snapshots created by the remote replication process are a special form called replication snapshots, which do not count against snapshot license limits. In order to perform a replication, a snapshot of the external-view volume is taken, creating a point-in-time image of the data. This point-in-time image is then replicated to the destination volume by copying the data represented by the snapshot using a transport medium such as TCP/IP (iSCSI) or Fibre Channel. The first replication copies all data from the source volume to the destination volume; subsequent replications use sparse snapshots. Replication snapshots are retained both on the external-view volume and the replication destination volume. When a matching pair of snapshots is retained on both volumes, the matching snapshots are referred to as replication sync points. The two snapshots (one on each volume) are used together as a synchronization reference point, minimizing the amount of data to transfer. The two snapshots in a sync point are assigned the same image ID, which uniquely identifies that the data in those snapshots are from the same point-in-time image and are block-for-block identical. An added benefit of using snapshots for replication is that these snapshots can be kept and restored later in the event of a non-hardware failure, such as virus attack. Since the replication source is a snapshot, any writes performed on the external view after the snapshot is taken are not replicated by that task. This gives you more control over what is contained in each replication image. NOTE: Because replication is not synchronous (continuous), data in a destination volume is only as current as the last replication that completed successfully. Replications can be performed manually or scheduled. 102 Using Remote Snap to replicate volumes

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102
Using Remote Snap to replicate volumes
Figure 4
Intersite and intrasite replication sets
Remote replication uses snapshot functionality to track the data to be replicated and to determine the
differences in data updated on the master volume, minimizing the amount of data to be transferred.
Snapshots created by the remote replication process are a special form called
replication snapshots
, which
do not count against snapshot license limits.
In order to perform a replication, a snapshot of the external-view volume is taken, creating a point-in-time
image of the data.
This point-in-time image is then replicated to the destination volume by copying the
data represented by the snapshot using a transport medium such as TCP/IP (iSCSI) or Fibre Channel. The
first replication copies all data from the source volume to the destination volume; subsequent replications
use sparse snapshots.
Replication snapshots are retained both on the external-view volume and the replication destination
volume.
When a matching pair of snapshots is retained on both volumes, the matching snapshots are
referred to as
replication sync points
.
The two snapshots (one on each volume) are used together as a
synchronization reference point, minimizing the amount of data to transfer. The two snapshots in a sync
point are assigned the same
image ID
, which uniquely identifies that the data in those snapshots are from
the same point-in-time image and are block-for-block identical.
An added benefit of using snapshots for replication is that these snapshots can be kept and restored later
in the event of a non-hardware failure, such as virus attack.
Since the replication source is a snapshot, any
writes performed on the external view after the snapshot is taken are not replicated by that task.
This gives
you more control over what is contained in each replication image.
NOTE:
Because replication is not synchronous (continuous), data in a destination volume is only as
current as the last replication that completed successfully. Replications can be performed manually or
scheduled.