HP StorageWorks B-Series Remote Replication Solution Best Practices Guide (5697-6731, June 2007)

the array c opies the data to the virtual disks in the destination D R group. Virtual d isks in a DR group fail
over together, share a write history log (DR group log), a nd preserve write order within the group.
Virtual d isks that contain data for one application must be in one DR group. For optimum failover
performance, limit the virtual disks in a DR group to as few as possible, and do not group virtual disks
that are assigned to separate applications.
The maximum number of virtual disks in a DR group and the maximum number of DR groups per array
vary with controller softw are versions. For current supported limits, see the latest HP StorageWorks EVA
replication software consolidated release notes.
DR group log
Plan for the additional disk space required for DR group logs. A D R group stores data in the DR group
log when:
• Aproblemoc
curs with the intersite link
• In suspended mode
• Using enhanced asynchronous write m od e
The log requires Vraid1 space ranging from 136 MB to 2 TB, with the maximum value depending on
the size of the DR g roup members and the version of controller software. (In later versions, you can
specify the maximum DR group log size.) For version support, see HP StorageWorks EVA replication
software consolidated release notes at the manuals location mentioned above. If XCS 6.0 or later is
being use
d, create the DR group log on an online drive . Constant writes to the DR group log in enhanced
asynchr
onous mod e significantly shortens the expected lifetime of near on-line drives.
HP cluster technologies for disaster-tolerant solutions
HP offers a comprehensive portfolio of disaster-tolerant solutions to protect the customer’s d a ta in
the event of disaster or system failure. Clustering technologies can be deployed in order to provide
automatic application failover and failback capabilities. This section will provide an overview of possible
technologies. All are built on the foundation of HP’s clustering software, HP Serviceguard™.
HP Serv
iceguard
HP Serv
iceguard™ is a high availability (HA) clustering solution that leverages the strength of HP’s
experience in the H A business, bringing the best-in-class m ission critical HP-UX technologies to the Linux
environmentandProliantandIntegrityservers. Theclusterkitincludeshighavailabilitysoftwarethat
enterprise customers require for 24x7 business operations.
It is designed to:
• Prote
ct applications from a wide variety of software and hardware failures
• Monitor the health of each server (node)
• Quickly respond to failur es, including system processes, system memory, LAN media and
adap
ters, and application processes
• Enable customers to cluster HP Proliant and Integrity server families with a choice of shared
storage, depending on requirements
For more information, see the website h
ttp://www.hp.com/go /ha.
HP Storageworks Cluster Extension EVA
HP StorageWorks Cluster Extension EVA™ offers protection against application downtime from fault,
failure, or site disaster by extending a local cluster between data centers over metropolitan distances.
CLX EVA integrates with open-system clustering software (Microsoft Cluster Service in the Windows
2003 environments and HP Serviceguard™ for Linux in Red Hat and SuSe Linux environments) and
HP StorageWorks Continuous Access EVA™ to automate failover and failback between sites. Cluster
Extension EVA™ delivers true hands-free failover/failback decision making - in the event the human
34
Solution setup