On Mon, Nov 12, 2007 at 09:24:34AM +0200, Jukka Marin wrote:
> Is there a way to limit the number of transfers to disk per second?  Or
> better yet, a way to limit the disk load ("%busy" in systat) to, say, 90%?
> Ideally, this should probably affect only ioflush, so other disk accesses
> would still be possible.  Or maybe there's an even better way of preventing
> the cache flush from overloading the disk(s)?

Have you tried using a different IO scheduler? There are kernel options
to give priority sorting and read-optimised scheduling. You can select
the policy for a device with dkctl $dev strategy. The default is first
come, first serve. It can also help to disable softdep :-)

Joerg