Reporting Target Path Groups; Tuning The Failover For Specific Host Bus Adapters; Configuring Multipath I/O For The Root Device - Novell LINUX ENTERPRISE SERVER 11 - STORAGE ADMINISTRATION GUIDE 2-23-2010 Administration Manual

Priority Value Description
1 The device is in the standby group.
0 All other groups.
Values are widely spaced because of the way the
the number of paths in a group with the priority value for the group, then selects the group with the
highest result. For example, if a non-optimized path group has six paths (6 x 10 = 60) and the
optimized path group has a single path (1 x 50 = 50), the non-optimized group has the highest score,
so multipath chooses the non-optimized group. Traffic to the device uses all six paths in the group in
a round-robin fashion.
On failure, returns a value of 1 to 5 indicating the cause for the command's failure. For information,
see the man page for
mpath_prio_alua

7.6.5 Reporting Target Path Groups

Use the SCSI Report Target Port Groups (
page for .
sg_rtpg(8)
7.7 Tuning the Failover for Specific Host Bus
Adapters
When using multipath I/O, you want any host bus adapter (HBA) failure or cable failures to be
reported faster than when multipathing is not in use. Configure time-out settings for your HBA to
disable failover at the HBA level to allow the failure to propagate up to the multipath I/O layer as
fast as possible where the I/O can be redirected to another, healthy path.
To disable the HBA handling of failover, modify the driver's options in the
modprobe.conf.local
to disable failover settings for your driver.
For example, for the QLogic qla2xxx family of host bus adapters, the following setting is
recommended:
options qla2xxx qlport_down_retry=1

7.8 Configuring Multipath I/O for the Root Device

IMPORTANT: In the SUSE Linux Enterprise Server 10 SP1 initial release and earlier, the root
partition ( ) on multipath is supported only if the
/
partition. Otherwise, no boot loader is written.
DM-MP is now available and supported for
To enable multipathing on the existing root device:
1 Install Linux with only a single path active, preferably one where the
in the partitioner.
2 Mount the devices by using the
multipath
.
sg_rtpg(8)
file. Refer to the HBA vendor's documentation for information about how
/boot
/boot
/dev/disk/by-id
command handles them. It multiplies
) command. For information, see the man
/etc/
partition is on a separate, non-multipathed
and in SUSE Linux Enterprise Server 11.
/root
by-id
path used during the install.
Managing Multipath I/O for Devices
symlinks are listed
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