Designing Disaster Recovery Clusters using Metroclusters and Continentalclusters, Reprinted October 2011 (5900-1881)

Data Replication Connections
The remote copy connections are the physical paths used by the primary array to communicate
with the secondary array. The primary P9000 or XP array and secondary P9000 or XP array are
connected using fiber-channel interface (Note: ESCON is not supported with the XP12000). Ensure
the connection is established in a bidirectional manner.
Metrocluster package vs. Journal Group
Metrocluster with Continuous Access for P9000 and XP supports only one journal group pair per
package. Thus, in a metropolitan cluster, the number of packages can be configured to use journal
group is limited by either the maximum number of journal groups that are supported by the P9000
or XP in the configuration, or by the maximum number of packages in the cluster, which ever is
smaller.
Metrocluster with Continuous Access for P9000 and XP and Thin Provisioning Volumes
Metrocluster with Continuous Access for P9000 and XP includes support for Thin Provisioning
Volumes (TP-VOLs) only on arrays XP20000, XP24000, P9500 and beyond, and P9000 disk array
family. When TP-VOLs are configured, there is a possibility that the TP-VOL utilization could exceed
the specified capacity or threshold of the pool. When this threshold is exceeded, the state of all
pool volumes are marked as BLOCKED. As a result, no I/O can be written to the TP-VOLs, and
subsequently, the Metrocluster package fails. However, the package failover fails in the remote
site, as the pools at the remote site are also marked as BLOCKED, since the configuration is symmetric
with the configuration at the primary site.
To overcome this problem, the pool utilization must be manually monitored to determine when the
predefined threshold is achieved. By monitoring the utilization, additional storage space can be
allocated to the pool as and when required.
For more information about configuring and monitoring Thin Provisioning volumes, see the HP
StorageWorks P9000 Provisioning for Open Systems User Guideor HP StorageWorks
XP24000/XP20000 Thin Provisioning Software User's Guide at:
http://bizsupport1.austin.hp.com/bizsupport/TechSupport/ProdSearch.jsp?
prod=HP%20StorageWorks —> HP StorageWorks XP Array Manager Software —> Manuals.
Following are the guidelines that must be considered for configuring Thin Provisioning Volumes in
a Continuous Access Pair:
• This feature is supported on arrays XP20000, XP24000, P9500 and beyond.
• The Primary Volumes (P-Vol) and Secondary Volumes (S-Vol) must be Thin Provisioning Volumes.
A combination of regular volumes with Thin Provisioning volumes is not supported.
• Only Continuous Access Synchronous and Journal configurations are supported with Thin
Provisioning Volumes.
• All synchronous fence levels with the values set as data and never are supported.
• Journal volumes cannot be TP-VOL.
• Pool volumes cannot be part of the Continuous Access pair.
• When pools used for a Metrocluster package are shared with other packages or applications,
ensure that the pools are not over provisioned by one application impacting the high availability
of the other applications.
• A Metrocluster package can have multiple pools or TP-VOL.
• Configure adequate monitoring and alerting mechanisms for the ThP pools.
Overview of Continuous Access P9000 and XP Concepts 163