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

• Hosts without multipathing soft ware
• Hosts with operating systems not supported by HP Continuous Access EVA (for suppor ted
operating systems, see HP StorageWorks EVA software compatibility reference)
• Incompatible stora ge system products (for compatible storage systems, see HP StorageWorks EVA
software compatibility reference); for example, HSG controllers with Data Replica tion Manager
Remote replication zones can include compatible offline tape devices.
Configure hosts
Configure native or installed multipath software on all hosts in remote replication configurations.
Multipathing software redirects I/O requests from a failed path to the alternate path, preventing
disruptions in data access if the path to the array fails. Multipath software is required for remote
replicatio
n. If the multipath software is Secure Path, turn off dynamic load ba lancing. See your multipath
documentat
ion for installation an d configuration information.
For support
ed host operating systems, see HP StorageWorks EVA soft ware compatibilit y reference.
Initialize the arrays and create disk groups
Initializing an array cre ates a default disk group of at least eight disks. To control the number and
composition of the disk groups in your array, install only the disks that you want in the first disk gr oup
and then initialize the array. Add disks and create additional disk groups as needed. For instructions to
initialize the array and add disk groups, see HP Command View EVA user guide and online help.
Determin
ing the number of disk groups
To determ
ine if the default disk group is sufficient for your remote replication needs, consider the following:
• Separate disk groups can ensure that data is recoverable if a disk group fails. On the other hand,
multiple disk groups result in a s lightly higher cost of own ership and potentially lower per formance.
To assess the trade-offs between cost, availability, and per formance of multiple disk groups versus
a sing le large disk group, see the HP StorageWorks Enterprise Virtual Array configuration best
practices white paper on the EVA web s ite.
• In gene
ral, distributing the workload across the greatest number of disks in a single disk group
provi
des the best performance. However, separate disk groups for sequential (database logs, rich
conte
nt) versus random (database information store, file shares) workloads can improve performance.
To understand performance and remote replication, see HP StorageWorks Continuous Access
EVA planning guide. To assess the effect of distance on performance, use HP StorageWorks EVA
Performance Estimator.
• Disk groups must provide sufficient free space for sparing, snapshots and snapclones (if used), and
DR group logs. For guidelines, see HP StorageWorks Enterprise Virtual Array con fi guration best
pra
ctices white paper.
• A DR group can contain virtual disks from multiple disk groups, but all virtual disks must be in the
same array.
• Bid
irectional replication requires symmetric disk groups on local and remote arrays.
Specifying disk group properties
Using HP Command View EVA, initialize each local and remote array and create additional disk groups
as needed. When c on fig uring disk groups for remote replication, consider the following:
• A ssign different names to local and remote arrays, or you will not be able to fail over DR groups.
• Select double disk protection level for disk groups. (This differs from the best practice in nonrep licating
configurations.) The protection level determines the capacity that is reserved for rec onstructing disks
after a disk failure. Selecting double reser ves the largest amount of disk capacity and provides the
most data protection.
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Remote replication setup