Lustre 1.6 Operations Manual

3.3.5 Changing the I/O Scheduler
There are two ways to change the I/O scheduler—at boot time or with new kernels
at runtime. For all Linux kernels, appending elevator={noop|deadline} to the
kernel boot string sets the I/O elevator.
With LILO, you can use the append keyword:
image=/boot/vmlinuz-2.6.14.2
label=14.2
append="elevator=deadline"
read-only
optional
With GRUB, append the string to the end of the kernel command:
title Fedora Core (2.6.9-5.0.3.EL_lustre.1.4.2custom)
root (hd0,0)
kernel /vmlinuz-2.6.9-5.0.3.EL_lustre.1.4.2custom ro
root=/dev/VolGroup00/LogVol00 rhgb noapic quiet elevator=deadline
With newer Linux kernels, youg can change the scheduler while running 3 . If the file
/sys/block//queue/scheduler exists (where is the block
device you wish to affect), it contains a list of available schedulers and can be used
to switch the schedulers.
(hda is the ):
[root@cfs2]# cat /sys/block/hda/queue/scheduler
noop [anticipatory] deadline cfq
[root@cfs2 ~]# echo deadline > /sys/block/hda/queue/scheduler
[root@cfs2 ~]# cat /sys/block/hda/queue/scheduler
noop anticipatory [deadline] cfq
For desktop use, the other schedulers (anticipatory and cfq) are better suited.
3. Red Hat Enterprise Linux v3 Update 3 does not have this feature. It is present in the main Linux tree as of
2.6.15.
3-8 Lustre 1.6 Operations Manual • September 2008