HP B6960-96035 - Manual (Page 268)

allows up to three replicas, and each can have an additional two copies if cascading
is used.
During the instant recovery, the data on the specified replica (left unchanged for the
purpose of instant recovery) is synchronized to the application client source volumes
without restoring from a backup medium.
Data Protector will only use the first three replicas because secondary mirrors cannot
perform fast-resynchronization, which is critical for ensuring minimal restore time.
Instant recovery is only possible using the HP StorageWorks BusinessCopy XP
configuration (local mirror - dual host and local mirror - single host configurations).
ZDB to tape and ZDB to disk+tape
During ZDB-to-tape and ZDB-to-disk+tape sessions, a replica of the application data
is streamed to a tape device, which is connected to a separate backup system, using
Data Protector Disk Agent and General Media Agent, with minimal impact on the
application system. After the backup is completed, the replica is either:
• discarded - ZDB to tape
• retained and can be used for instant recovery - ZDB to disk+tape
ZDB to disk
During a ZDB-to-disk session, the original data is not moved to a backup medium
(tape) from the replica. The replicas (up to three) can be used for various purposes,
such as offline data processing or instant recovery; the latter is possible only if HP
StorageWorks BusinessCopy XP configuration was used. It is only possible to restore
objects from a ZDB-to-disk session by using the instant recovery functionality.
Replica set rotation
Several replicas can exist at the same time. HP StorageWorks Disk Array XP allows
up to three replicas, and each can have an additional two copies if cascading is
used. Data Protector can use only disks from the first three replicas (first level mirrors
or MUs) for backup and instant recovery purposes. The additional six copies
(cascading mirrors) are not supported.When configuring a ZDB backup specification
for a source volume (LDEV) with first level mirrors configured or when restoring to
such a source volume, it is, using Data Protector, possible to define a replica set from
which this integration selects one replica for the current session.
Backup clients and clusters
The backup client should not be used as a failover server for the application client.
It is recommended to have application and backup services on separate clusters.
Split mirror concepts 268