10.0 Multipath IO
Linux multipathing provides IO failover and path load sharing for
multipathed block devices. The multipath IO support in SUSE® Linux Enterprise Server is based on
the Device Mapper multipath module of the Linux kernel and the
multipath-tools userspace package.
Device mapping multipath IO features automatic configuration of the
subsystem for a large variety of setups. Active/passive or active/active
(with round-robin load balancing) configurations of up to eight paths to each
device are supported.
multipath-tools take care of automatic path
discovery and grouping as well as automated path retesting, so that a
previously failed path is automatically reinstated when it becomes healthy
again. This minimizes the need for administrator attention in a production
environment.
Device mapping multipath IO supports partitions (with limitations) and
LVM2. Software RAID is also supported, but automatic discovery is not
available.
To use software RAID with mdadm, /etc/mdadm.conf must be
set up correctly. See Section 10.4,
Using the Devices for more information.
Currently, device mapping multipath IO is not available for the boot
partition, because the boot loader cannot handle multipath IO. Therefore it
is recommended to set up a separate boot partition when using multipath IO.
