Very low disk performance on 5.x

[kama]

On Mon, 2 May 2005, Eric Anderson wrote:

> I'll be honest here, I don't care much if the speed difference between
> 4.X and 5.X is measureable, or whatever.  What I find is a little
> telling of an issue somewhere, is that READS are slower than WRITES!
> This is totally bogus to me - dd'ing a file to a filesystem, then
> umounting should take longer than dd'ing from the disk to /dev/null, it
> nearly every config I can dream up.  Maybe it's the speed at which
> /dev/null can gobble bits (seems highly unlikely!), or maybe GEOM is
> busy doing a check or some routine to data being accessed directly from
> the disk device instead of through a filesystem?  I don't know, but it
> is an issue, and I'm sure we'll get nailed up to a fence in some
> benchmark somewhere if we don't fix it..

dev-null is not the issue... my own written testprogram that only read up
data to a buffer in memory showed the same results as doing a dd to
dev-null.

/Bjorn