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
