Remote Replication Guidelines - HP 418800-B21 - StorageWorks Modular Smart Array 70 Storage Enclosure User Manual

• The destination DR group was unavailable after power was cycled off and on in the source array.
• Remote replication was not suspended after power was cycled off and on in the source array.
• The Destination mode was other than Read Only after power was cycled off and on in the
source array.
You can determine if disk presentation is blocked by checking the operational state of the DR group or
individual disk. See
Unblocking
The virtual disks in a source DR group are automatically unblocked when the destination DR group
becomes available again. You can manually unblock virtual disks by suspending the source DR group in
which they are members. See
Presentation blocking provides protection
Disk presentation blocking is a feature that is similar to failsafe operation. See
Blocking can provide the following:
• Data consistency during a site failure, when a source and its destination virtual disk could be
simultaneously presented to different hosts.
• Protection in stretched-host clusters, against host members accessing two copies of the same data.
• Protection for boot-from-SAN servers, against two hosts booting from the same boot image.

Remote replication guidelines

Storage arrays
• Source and destination arrays must have remote replication licenses. See
replication licenses
• The array selected for the destination DR group depends on the remote replication configuration.
For supported configurations, see the HP StorageWorks Continuous Access EVA planning guide.
• A storage array can have DR group relationships with up to two other storage arrays.
• The maximum number of virtual disks in a DR group and the maximum number of DR groups per
array vary with controller software versions. See
DR groups and failover
• Failover of a DR group pair is permitted only by specifying a destination DR group.
• When failsafe mode is enabled, a DR group pair cannot be suspended. See
failsafe on unavailable
• When a DR group pair is suspended, it cannot be failed over or reverted to home.
• A DR group cannot be deleted if a virtual disk in the destination DR group is presented.
• For additional help on usage, see
Log disks
• Logs disks for the source and destination DR groups should be kept the same size.
• The log size cannot be changed when in enhanced asynchronous write mode. See
Write mode
• The write mode cannot be changed if the source log disk is in use or contains data. Before
changing, a non-empty source log disk must be merged to its destination.
• If a source and destination array are not running the same implementation of write mode
(standard or enhanced), then only synchronous can be selected.
viewing DR group properties
suspending a DR group
overview.
member, suspend on
using DR
and viewing virtual disk
pair.
controller software features - remote
failover.
groups.
HP StorageWorks Replication Solutions Manager 4.0.1
properties.
failsafe mode.
replication.
write mode.
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