The Schedular is CFQ and can be changed on the fly to whatever Block Device you want it. It does not matter what load the system is under. Changing to Deadline on his specific block device will improve the I/O of the system unless it really being hammered. Keep in mind these changes will be gone on Reboot. You can put these in rc.local to activate at boot time. Substitute "hda" for your device. This does not work on iscsi or SAN mounts.
[root@blah ~]# echo 'deadline' > /sys/block/hda/queue/scheduler [root@blah ~]# cat /sys/block/hda/queue/scheduler noop anticipatory [deadline] cfq -- Changed to Deadline.
echo 'deadline' > /sys/block/sda/queue/scheduler -bash: /sys/block/sda/queue/scheduler: No such file or directory
ls -l /sys/block/sda/queue/ total 0 drwxr-xr-x 2 root root 0 Dec 8 17:45 iosched -r--r--r-- 1 root root 4096 Dec 10 10:10 max_hw_sectors_kb -rw-r--r-- 1 root root 4096 Dec 10 10:10 max_sectors_kb -rw-r--r-- 1 root root 4096 Dec 10 10:10 nr_requests -rw-r--r-- 1 root root 4096 Dec 10 10:10 read_ahead_kb
No go.
Matt