HP P6000 Cluster Extension Software Administrator Guide (5697-0986, June 2011)

Finding the user-friendly name of a multipath device
The multipath_rescan.sh script requires that you enter the user-friendly names of the multipath
devices. To obtain the user-friendly name of a multipath device:
1. Run the pvs command to view the multipath device names for your volume groups.
In the following example, dm-21 and dm-23 are the multipath devices for the volume group
vg01:
[root@node1 ]# pvs
PV VG Fmt Attr PSize PFree
/dev/dm-21 vg01 lvm2 a- 1.82G 0
/dev/dm-23 vg01 lvm2 a- 1.82G 0
/dev/dm-24 vg02 lvm2 a- 1.82G 0
2. Obtain the SCSI ID for a multipath device. Use the scsi_id command for SUSE Linux Enterprise
Server, and the hp_scsi_id command for Red Hat Enterprise Linux.
SUSE Linux Enterprise Server:
[root@node1 ]# scsi_id -guns /block/dm-21
360060e8014424600000142460000039d
Red Hat Enterprise Linux:
[root@node1]# hp_scsi_id -guns /block/dm-14
360060e8014424600000142460000039d
3. Use the multipath command to obtain the user-friendly name for the multipath device's generated
SCSI ID. In the following example, mpathq is the user-friendly name of a multipath device:
[root@node1]# multipath -ll | grep 360060e8014424600000142460000039d | awk
'{print $1}' mpathq
Timing considerations
P6000 Cluster Extension Software gives priority to storage system operations over cluster software
operations. If P6000 Cluster Extension is invoked during a DR group member resynchronization
(merge), or is gathering information about the remote storage system, it waits until the requested status
information is reported. This ensures the priority of data integrity over cluster software failover processes.
This behavior can lead to failed resources:
• When P6000 Cluster Extension uses HP SMI-S to communicate with the HP P6000/EVA storage
system, depending on the setting of the SMI-S request timeout parameter and the number of retries,
the operation can time out. This can happen when several management servers are used with
P6000 Cluster Extension and the P6000/EVA storage system is busy processing other management
commands.
• When a DR group member resynchronization (merge) is in progress, the software waits until the
DR group is in a normal state if the ApplicationStartup resource property is set to RESYNCWAIT.
• In an SLE HA environment, if the ResyncWaitTimeout object value is higher than the resource
startup timeout value.
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