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SLES 10 SP3: Storage Administration Guide
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5.2.3 Using LVM2 on Multipath Devices
By default, LVM2 does not recognize multipathed devices. To make LVM2 recognize the
multipathed devices as possible physical volumes, you must modify
/etc/lvm/lvm.conf
. It is
important to modify it in a way that it does not scan and use the physical paths, but only accesses the
multipath I/O storage through the multipath I/O layer.
To modify
/etc/lvm/lvm.conf
for multipath use:
1
Open the
/etc/lvm/lvm.conf
file in a text editor.
2
Change the
filter
and
types
entry in
/etc/lvm/lvm.conf
as follows:
filter = [ "a|/dev/disk/by-id/.*|", "r|.*|" ]
This allows LVM2 to scan only the by-id paths and reject everything else.
3
If you are also using LVM2 on non-multipathed devices, make the necessary adjustments to
suit your setup.
4
Save the file.
5
Add dm-multipath to
/etc/sysconfig/kernel:INITRD_MODULES
.
6
Make a new
initrd
to ensure that the Device Mapper Multipath services are loaded with the
changed settings. Enter
mkinitrd -f mpath
7
Reboot the server to apply the changes.
5.2.4 Using mdadm with Multipath Devices
The
mdadm
tool requires that the devices be accessed by the ID rather than by the device node path.
Therefore, the
DEVICE
entry in
/etc/mdadm.conf
should be set as follows:
DEVICE /dev/disk/by-id/*
This is the default handling in SUSE Linux Enterprise Server 10 and later.
5.2.5 Using --noflush with Multipath Devices
The option --noflush should always be used when running on multipath devices.
For example, in scripts where you perform a table reload, you use the --noflush option on resume to
ensure that any outstanding I/O is not flushed, because you need the multipath topology information.
load
resume --noflush
5.2.6 Partitioning Multipath Devices
SUSE Linux Enterprise Server 10
In SUSE Linux Enterprise Server 10, the
kpartx
software is used in the
/etc/init.d/
boot.multipath
to add symlinks to the
/dev/dm-*
line in the
multipath.conf
configuration file
for any newly created partitions without requiring a reboot. This triggers
udevd
to fill in the
/dev/
disk/by-*
symlinks. The main benefit is that you can call
kpartx
with the new parameters without
having to reboot the server.
Summary of Contents for LINUX ENTERPRISE SERVER 10 SP3 - ARCHITECTURE-SPECIFIC
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