Performing Initial Replication Locally Or Remotely; Remote Replication Disaster Recovery - HP P2000 G3 Reference Manual
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Delta replications: Delta data is the "list" of 64-Kb blocks that differs between the last snapshot
replicated and the next snapshot to be replicated. This delta data is then replicated from the
replication snapshot on the primary volume to the secondary volume. Once the initial replication has
completed, all future replications for that replication set will be delta replications so long as sync points
are maintained. Action 5 is a delta replication.
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Queued replications: New replications can be initiated while other replication snapshots are in the
process of being replicated. This enables you to take snapshots at specific intervals while other
replications are ongoing. Note that a replication that is initiated while another to the same secondary
volume is ongoing will be queued, and will not begin to transfer data until the prior one completes. In
action 3, Snap 2 is queued while Snap 1 is being replicated; in action 7, Snap 3 is queued while Snap
2 is being replicated.
An in-progress replication can be suspended, either manually by a user or automatically if a network error
occurs. If you want the replication to continue, you must manually resume it; or, if you want to cancel the
replication, you can abort it.
IMPORTANT:
the controller that owns the primary volume. This link must be of the type specified by the link-type
parameter supplied during replication set creation or modification. If all links to the controller that owns the
primary volume fail, but links remain between its partner controller and the controller that owns the
secondary volume, replications currently in progress or queued may continue, but their progress may not
be reported correctly; replications requested after the links fail will not start replicating. If the controller that
owns the secondary volume loses all links to both controllers of the primary system, then the replications
will suspend and progress will be updated appropriately; links from the partner controller of the controller
that owns the secondary volumes are not considered for use. Replications that enter the suspended state
must be resumed manually.
Performing initial replication locally or remotely
When you set up replication for a volume, you specify to use a secondary volume in a vdisk in either the
local (primary) system or a remote (secondary) system.
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If the speed of the initial replication is most important, specify a vdisk that is owned by the same
controller as the primary volume's vdisk in the local system.
After replication is set up, you can perform the initial replication and then physically move the vdisk
containing the secondary volume and its snap pool into a remote system. Moving a vdisk involves using
SMU to detach the secondary volume and stop its vdisk, removing the vdisk's disks or enclosure,
transporting the disks or enclosure to the remote location, inserting the disks or enclosure into the
remote system, and using SMU to restart the vdisk and reattach the secondary volume. If the secondary
volume's snap pool is in a different vdisk then that vdisk must also be stopped, moved, and restarted.
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If ease of setup is most important, specify a vdisk owned by either controller in a remote system. After
replication is set up, you can start replication.
In either case, you must specify whether FC or iSCSI links will be used for replication between the primary
and secondary systems and you cannot change this setting for the life of the replication set.
Remote replication disaster recovery
Replication can continue in the event of system faults such as:
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Temporary communication failure. Remote replication will retry replication operations according to
user-configured policies.
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Controller failure. In a dual-controller system, failover will occur and the surviving controller will take
over replication processing until controller recovery occurs.
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Disk or power supply failure.
If a disaster causes the primary volume to become inaccessible, you can set the secondary volume to the
primary volume so that volume can be mapped to hosts. Disaster recovery requires user intervention
because decisions must be made based on the data content of replication volumes and their snapshots.
108 Using Remote Snap to replicate volumes
For a replication to begin, the controller that owns the secondary volume must have a link to
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