Re: RAID halting

[Andrew Burgess <aab@cichlid.com>]

On Wed, 2009-04-08 at 10:37 -0400, Greg Freemyer wrote:

> I think the only way to switch schedulers is to reboot.  You invoke
> the noop scheduler via a command line arg to the kernel at boot time.

This can be done at any time, no reboot required:

 for f in /sys/block/*/queue/scheduler; do
    echo noop > $f
    echo $f "$(cat $f)"
  done

Just FYI, I don't think ionice and friends will work when using noop.

Leslie: I still think finding out what the kernel is doing during the
stall would be a HUGE hint to the problem. Did you look into oprofile or
ftrace?