Managing HP Serviceguard for Linux, Seventh Edition, July 2007

Understanding Serviceguard Software Components
Volume Managers for Data Storage
Chapter 382
NOTE LUN definition is normally done using utility programs provided by the
disk array manufacturer. Since arrays vary considerably, make sure you
read the documentation that accompanies your storage unit.
Multipathing and LVM
How multipathing is implemented depends on the storage sub-system
attached to the cluster and the HBA in the servers. Check the
documentation that accompanied your storage sub-system and HBA.
• For fibre-channel storage, use the multipath function within the
HBA driver, if that function is supported by HP.
— For the QLogic driver, refer to the application note “Using the
QLogic HBA driver for single-path or multipath failover mode on
Linux systems”, which you can find by entering the terms “qlogic
multipath application” in the search box of www.hp.com.
Once you have created the LUNs, configure each LUN into LVM as a
single physical volume, following the directions in chapter 5 (the
multiple paths are hidden by the driver).
NOTE Serviceguard does not support the multiple device driver (MD) for
fibre-channel storage, nor does it support the Device Mapper (DM).
• For MSA 500 family devices that support multipathing, use the MD
driver. Use the mdadm command to create a multipath device, then
configure the device into LVM as a single physical volume. For
example, you might use the command
mdadm –create /dev/md0 --level=multipath --raid-devices=2 /dev/sdf1 dev/sdh1
to create a multipath device from devices /dev/sdf1 and /dev/sdh1.
Then configure /dev/md0 into LVM as a single physical device,
following the directions in chapter 5.