Re: [squid-users] Hard Drive Latency

On Mon, 30 Aug 2004, James Gray wrote:

> Is there anything to be gained by switching to AUFS in a SCSI RAID 0+1 (real
> hardware RAID with 64MB cache etc) environment?

Yes.

What aufs solves is mainly the read latency blocking the whole operation
of Squid. A RAID does not help.

> We often see system (i.e., not "nice" or "user") utilisation go up under
> heavy Squid load on FreeBSD, but I can't say whether or not this results in a
> noticeable performance degradation - we've never measured it and the users
> haven't complained (about proxy performance anyway).

aufs is not designed for FreeBSD. On FreeBSD you should be using diskd.

for aufs to work it requires that your OS implements kernel threads,
making sure that one thread being blocked by disk I/O does not block the
whole process.

diskd addresses the same issues as aufs, but is implemented in a different
manner (helper process rather than threads).

Regards
Henrik
Received on Mon Aug 30 2004 - 00:37:33 MDT