HP XP Racks - Manual (Page 27)

4 Working with volume pairs
A number of tasks must be performed on volume pairs as part of your normal ESAM system
maintenance activities, when troubleshooting system issues, or when taking action to recover from
failure.
Workflow for ESAM volume pairs
You perform several different types of tasks with volume pairs as part of your system maintenance
and recovery activities.
The different types of tasks include:
•
Checking pair status.
•
Creating pairs.
•
Releasing pairs.
•
Resynchronizing pairs.
•
Splitting pairs.
All of the different pair-related tasks can be performed using RWC or RAID Manager.
Reasons for checking pair status
Pair status information indicates the current state or condition of the pair.
There are two main reasons for checking the current status of a volume pair. One is to verify the
status of the pair while you run pair RAID Manager commands during normal system maintenance
or failure recovery. The other reason is to check the status of pairs as part of your normal system
monitoring activities to ensure they are working properly.
When to check pair status?
You should check the status of volume pairs whenever you run pair RAID Manager commands and
as part of your normal system monitoring activities.
When you run pair RAID Manager commands, you check pair status:
•
Before you run a pair RAID Manager command.
•
During pair changes. Check pair status to see that the pairs are operating correctly and that
data is updating from P-VOLs to S-VOLs in PAIR status, or that differential data management
is happening in Split status.
NOTE: You can perform a pair task can only be completed if the pair is in a status that permits
the task. Checking the status before you run a RAID Manager command lets you verify that the
pair is in a status that permits the task.
How pair status reflects system events and use
The storage system records information about the current status of ESAM pairs. You can check the
current status of any volume pair at any time.
Status changes occur for the following reasons:
•
Automatic system events, such as errors or failover situations.
•
Administrator actions, such as creating, releasing, or deleting pairs.
The following figure shows ESAM pair status before and after pair creation, splitting pairs, various
errors, and after releasing a pair.
Workflow for ESAM volume pairs 27