Re: Strange delete performance using XFS
On Thu, Apr 05, 2007 at 03:25:31PM +0200, martin f krafft wrote:
> also sprach Thomas Kaehn <email@example.com> [2007.04.05.1424 +0200]:
> > However disabling write barriers is the only measure which lowers
> > delete performance from minutes to seconds. I've opened a case at
> > 3ware to come to know if write barriers are supported by the
> > controller.
> Good. I would be interested in their response.
> > As write barriers are "generally recommended" according to the XFS
> > FAQ I don't want to disable them (which might be negative in case
> > of system crashes).
> Yeah, definitely.
3ware didn't answer yet. However I've found an option in the controller
to set the "storsave" policy.
In the default profile FUA (force unit access) commands are only
acknowledged directly in case a BBU is present. Otherwise the controller
waits until the data is written to disk.
When selecting the "performance" profile FUA commands are ignored and
delete time decreases to a couple of seconds.
So the behaviour of the controller should be considered a feature. But
I am still astonished how slow deletes were in the first place.
This might be a bug or incompatibility anyhow.
Thanks to all others for your suggestions. I'll inform you in case
3ware has news for me.
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