HP XP7 Storage - Manual (Page 11)

system. RAID Manager provides a full scripting capability that can be used to automate
replication operations.
•
Business Continuity Manager (BCM), which is a command line interface from which pair
operations are run and pair status is monitored. BCM commands are issued from the host to
the storage system.
•
PPRC, with which most operations can be performed from the host. All XP7 storage systems
support IBM PPRC host software functions.
Failover software
Host failover software is used to transfer information between host servers at the local and remote
sites. It is a critical component of any disaster recovery solution.
•
When Continuous Access Synchronous Z is used as a disaster recovery tool, host failover is
required to ensure effective recovery operations.
•
When Continuous Access Synchronous Z is used as a data migration tool, host failover is
recommended.
Continuous Access Synchronous Z does not provide host failover functions. Use the failover software
most suitable for your platform and requirements (for example, Microsoft Cluster Server).
Error reporting communications
Error reporting communications (ERC) transfers information between host processors at the main
and remote sites. It is a critical component of a disaster recovery effort.
Overview of initial, update copy operations
When you perform the initial copy operation, all the data in the P-VOL is copied into the S-VOL.
Thereafter, the primary storage system runs update copy when it receives write instruction from the
host. The update operation copies host updates to the S-VOL at the same time that they are copied
to the P-VOL.
The following figure illustrates the initial copy and update copy operations.
Initial copy
When a new pair is created, the entire contents of the P-VOL are copied to the S-VOL cylinder by
track (this does not include diagnostic and unassigned alternate tracks). The initial copy synchronizes
the P-VOL and S-VOL independently of host I/O processes.
During the create pair operation, you can elect to have no data copied if data in the P-VOL and
S-VOL are already identical. You can also specify options that affect the speed of data transfer
and storage system performance. These are:
•
Copy Pace. You specify the number of tracks that can be copied simultaneously before the
primary system accepts another host request for that P-VOL. If more tracks are copied, the
operation completes quicker; if fewer tracks are copied, performance is maintained at a higher
level.
•
Maximum Initial Copy Activities. You specify the maximum number of concurrent initial copies
that the system performs.
Failover software 11