HP XP Racks - Manual (Page 54)

Recovery from blocked pair volumes
In most cases, a blocked volume pair results in automatic failover. This helps to ensure that host
I/O continues and host applications remain available.
The process used to recover pair volumes from this failure varies depending on:
•
Whether the volume is a primary or secondary volume.
•
Whether the volume is in the primary or secondary storage system.
Depending on which systems and volumes are affected and whether failover occurred, the recovery
process can involve:
•
Releasing the pair
•
Clearing the failure
•
Clearing any other failures that may prevent normal host I/O
•
Recreating the pair
•
Restoring the original relationship of the volumes
•
Restoring normal host I/O (or restarting host I/O)
The following figure shows the different volume failure scenarios that are possible with volume
pairs.
1. “Recovering from primary volume failure on the MCU” (page 54) .
2. “Recovering from secondary volume failure on the MCU” (page 55) .
3. “Recovering from primary volume failure on the RCU” (page 56) .
4. “Recovering from secondary volume failure on the RCU ” (page 57) .
Recovering from primary volume failure on the MCU
When this failure occurs, automatic system failover switches host I/O to the primary volume on
the RCU. Recovering the volume from this failure involves releasing the pair, clearing the failure,
recreating the pair, restoring the original relationship of the volumes, and restoring normal host
I/O.
NOTE: If the failed volume is an external volume, contact the HP Support Center for assistance
clearing the failure.
You use multipath software and either RWC or RAID Manager to complete the recovery procedure.
TIP: Some of the steps can be performed by using either RWC or RAID Manager. Typically, you
can complete these steps quicker using RAID Manager.
1. Using multipath software, make sure that the secondary storage system is receiving host I/O.
2. Stop I/O from the host.
54 Disaster recovery