Managing HP Serviceguard A.11.20.10 for Linux, December 2012

4.3.3 Shared Storage
SCSI can be used for up to four-node clusters; FibreChannel can be used for clusters of up to 16
nodes.
4.3.3.1 FibreChannel
FibreChannel cards can be used to connect up to 16 nodes to a disk array containing storage.
After installation of the cards and the appropriate driver, the LUNs configured on the storage unit
are presented to the operating system as device files, which can be used to build LVM volume
groups.
NOTE: Multipath capabilities are supported by FibreChannel HBA device drivers and the Linux
Device Mapper. Check with the storage device documentation for details.
See also “Multipath for Storage ”.
You can use the worksheet to record the names of the device files that correspond to each LUN
for the Fibre-Channel-attached storage unit.
4.3.3.2 Multipath for Storage
The method for achieving a multipath solution is dependent on the storage sub-system attached to
the cluster and the Host Bus Adapters (HBAs) 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, see “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 into the search box of www.hp.com.
NOTE: With the rapid evolution of Linux, the multipath mechanisms may change, or new ones
may be added. Serviceguard for Linux supports DeviceMapper multipath (DM-MPIO) with some
restrictions; see the Serviceguard for Linux Certification Matrix at the address provided in the
Preface to this manual for up-to-date information.
NOTE: md also supports software RAID; but this configuration is not currently supported with
Serviceguard for Linux.
4.3.4 Disk I/O Information
You may want to use the Hardware worksheet in Appendix C to record the following information
for each disk connected to each disk device adapter on the node:
Bus Type Indicate the type of bus. Supported buses are SAS (Serial Attached SCSI)
and FibreChannel.
LUN Number Indicate the number of the LUN as defined in the storage unit.
Slot Number Indicate the slot number(s) into which the SCSI or FibreChannel interface
card(s) are inserted in the backplane of the computer.
Address Enter the bus hardware path number, which is the numeric part of the
host parameter, which can be seen on the system by using the following
command:
cat /proc/scsi/scsi
Disk Device File Enter the disk device file name for each SCSI disk or LUN.
This information is needed when you create the mirrored disk configuration using LVM. In addition,
it is useful to gather as much information as possible about your disk configuration.
78 Planning and Documenting an HA Cluster