Novell LINUX ENTERPRISE SERVER 10 - STORAGE ADMINISTRATION GUIDE 7-2007, Administration Manual

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Managing Multipath I/O for Devices 51
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cp /usr/share/doc/packages/multipath-tools/
multipath.conf.synthetic /etc/multipath.conf
3 Open the
/etc/multipath.conf
file in a text editor.
4
Uncomment the
Defaults
directive and its ending bracket.
5 Uncomment the
user_friendly_names option
, then change its value from No to Yes.
6 Specify names for devices using the ALIAS directive.
7 Save your changes, then close the file.
5.9 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 propogate 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
/etc/
modprobe.conf.local
file. Refer to the HBA vendor’s documentation for information about
how 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
5.10 Configuring Multipath I/O for the Root
Device
In the initial release, the root partition on multipath is supported only if the
/boot
partition is on a
separate, non-multipathed partition. Otherwise, no boot loader is written.
NOTE: This issue is resolved in updates since the initial release.
To enable multipathing on the existing root device:
1 Install Linux with only a single path active, preferably one where the
by-id
symlinks are
listed in the partitioner.
2 Mount the devices using the
/dev/disk/by-id
path used during the install.
3 After installation, add
dm-multipath
to
/etc/sysconfig/
kernel:INITRD_MODULES
.
4
Re-run
/sbin/mkinitrd
to update
initrd
image.
5 Reboot the server.
To disable multipathing on the root device:
1 Add
multipath=off
to the kernel command line.