HP Serviceguard for Linux Version A.11.16 Release Notes, Third Edition, August 2006

Serviceguard for Linux Version A.11.16 Release Notes
Compatibility Information and Installation Requirements
Chapter 122
Multipath for Storage
The method for achieving a multipath solution is dependent on the
storage sub-system attached to the cluster and the HBA in the servers.
Please check the documentation that accompanied your storage
sub-system and HBA.
For fibre channel attached storage, the multipath function within the
HBA driver should be used, if it is supported by HP. For the QLogic
driver refer to: “Using the QLogic HBA driver for single-path or
multipath failover mode on Linux systems application note”, which you
can find by entering the terms “qlogic multipath application” in the
search box of www.hp.com.
The use of the multiple device driver (md) is not supported for fiber
channel-based storage systems. It is supported with Serviceguard and
MSA 500 family devices that support multipath.
For md multipath, do not use any “ md” lines in the Serviceguard package
control scripts. Instead, for multipath only, md activation can be done at
system boot.
The following example creates a multipath device where the two devices
are /dev/sdf1 and /dev/sdh1:
mdadm –create /dev/md0 -level=multipath -raid-devices=2
/dev/sdf1 /dev/sdh1
The command to activate /dev/md0 would be:
mdadm –assemble –scan /dev/md0
This command can be added to the sysinit file.
The above is a simple example. Refer to the mdadm man page for more
information. The man page has a link to a “HOWTO” as well.
NOTE With the rapid evolution of Linux, the multipath mechanisms may
change, or new ones may be added. As of the date of this manual, device
mapper (DM) is not supported with Serviceguard for Linux.