Data Path; Consistency Groups; Interfaces; Failover Software - HP StorageWorks P9000 User Manual

specified for the R-VOL. Then, write I/O is allowed to the R-VOL while the pair is suspended. In
this instance, R-VOL and M-VOL track maps keep track of differential data and are used to
resynchronize the pair.
Volumes on the local and remote systems must be defined and formatted prior to pairing.

Data path

Continuous Access Synchronous Z operations are carried out between local and remote disk arrays
connected by a Fibre Channel interface. The data path, also referred to as the remote copy
connection, connects ports on the local P9500 system to the ports on the remote disk array. The
ports are assigned attributes that allow them to send and receive data.
One data path connection is required, but two or more independent connections are recommended,
for hardware redundancy. A maximum of eight paths per control unit (CU) can be used.

Consistency groups

A consistency group is a set of volume pairs that are in the same main and remote system on which
copy operations are performed simultaneously, and in which the pairs status remains consistent.
When you issue a command, it is executed on all pairs in the group. The pairs pair status changes
at the same time, depending on the group options.
Yet, while consistency is a primary function of a group, certain operations take priority. For example,
if the Suspended commend is issued to a consistency group in which one of the pairs is in the
process of being updated, the pair is not suspended immediately, as all the other pairs are. It is
suspended only when the update operation is completed. This allows for data integrity to be
maintained between M-VOLs and R-VOLs. The same behavior occurs for a suspended operation
caused by system failure.
Continuous Access Synchronous Z operations can be performed on pairs in a maximum of 128
consistency groups on the main system.

Interfaces

You perform Continuous Access Synchronous Z operations using any of the following interfaces:
Remote Web Console, a browser-based interface from which Continuous Access Synchronous
Z can be setup, operated, and monitored. The GUI provides the simplest method for performing
operations, requiring no previous experience.
The main disk array must be LAN-attached to a Remote Web Console computer.
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The remote disk array should also be LAN-attached to a separate Remote Web Console
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at the remote site. This allows you to perform operations more efficiently on the remote
disk array in the event that the main site is not available.
Configuration, pair operations, and pair status monitoring can be performed using Business
Continuity Manager commands from the host to the disk array.
Most operations can be performed using PPRC commands from the host. All P9500 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 insure effective recovery operations.
When Continuous Access Synchronous Z is used as a data migration tool, host failover is
recommended.
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