HP StorageWorks Continuous Access EVA Administrator Guide (T3687-96043, December 2005)

Using HP Replication Solutions Manag er o r HP Command View EVA, create DR groups on the local
(source) array. At a m inimum, you must specify a source virtual disk and a destination array. The array
software creates a corresponding DR group and virtual disk on the remote array.
Specifying vi
rtual disks
Select one vir
tual disk to create the source DR group. If this and other virtual disks are assigned to an
application that requires write order to be consistent across the virtual disks, add the other virtual disks
to the DR group. A database application, for example, may require consistent writes across separate
virtual disks for data and logs. For optimum performance, do not mix virtual disks assigned to multiple
application
sinaDRgroup.
To be eligibl
eforinclusioninaDRgroup,asourcevirtualdisk:
• Cannot be a member of another DR group
• Cannotbeasnapshot
• Must be in no
rmal operational state
• Must use mirrored write cache (the default)
• Must have the same presentation status as other virtual disks in the DR group
Specifying DR group log location and size
You can specify the location of the DR group log when you crea te a DR group. By d efault, the array
software crea tes a 139–MB log on local and remote arrays, using a near-online (FATA) d isk g roup if
available. If there are no near-online drives, the software selects the disk group with the l argest amount of
average free space. HP recommends using the same priorities when you specify the log disk gro up.
You can also specify the size of the DR g roup log that is considered full and thereby influence the point at
which the software abandons the log and starts a full copy. The value must be less than 2 TB, or it has
no effect. If the disk group runs out of free space, the software starts a full copy regardless of the value
specified. For the default maximum size, see the EVA replication software release notes.
The ability to specify DR group log location and size is not supported on VCS 3.x.
Select
ing replication mode
Select
the replication mode when you create a DR group. Synchronous is the default a n d the most reliable
repli
cation mode, providing identical copies on lo cal and remote arrays at all times. Asynchronous offers
faste
r responses to host servers and potentially greater lags between local and remote writes. The
choi
ce of re plication mode has design implications and depends on business requirements. For detailed
desc
riptions of synchronous and asynchronous modes, see the HP Continuous Access EVA planning guide.
Present destination virtual disks
After creating the DR groups, present the destination virtual disks to the hosts that the source virtual disks
are presented to. This enables local hosts to access data at the remote site if the local array fails and
DR groups are failed over. Also present destination virtual disks to the remote hosts that will be used if
the local site fails and server software is used to fail over applications. Use HP Command View EVA or
the replication m anager to present destination virtual disks to hosts.
Back up the configuration
Back up your storage and replication c on figuration now and anytime it changes. Regular backups are
essential to effective disaster recovery. You can use the initial backup to re-create the configuration
on
remote and standby management servers. For backup procedures, see Backing up replication
co
nfiguration.
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Remote replication setup