Re: disk layout + performance

From: Ong Beng Hui <>
Date: Tue, 11 Feb 1997 00:12:07 +0800 (SST)

> Our two cache servers are running with Solaris 2.5 and 2.5.1 and using
> DiskSuite to stripe 4x2Gb discs into a single partition for the /squid/cache
> directory. We're using striping, rather than multiple directories,
> because experience has shown it to noticeably increase performance in
> other similar applications. So far it seems to work very well.

I am a little doubtful about the usefulness on striping for
Squid. The reason is such that with striping, you basically
tie all the heads together. So access to the disks is limited
to one access at one time. I would think that using each of the
disks as a single cache_dir would be better since the simultaneous
access will be possible to each individual dusks.

I got a 20 % increase in load handling when I change 3 x 4 Gig
stripped set to single disk and from AdvFS to UFS. But the 20%
might come partly from the change from AdvFS to UFS. I am using
Digital UNIX on a DEC AlphaServer 4100 with 3 SCSI channels.

With Async I/O in place for Solaris, I would expect a better
performance without stripping.

I think that stripping will be useful when there is a need
for a large disks, as well as higher performance if the
disk access is more sequential. But for Squid/Harvest, the
access is very random, and very small. Average object size
will be around the region of 20K for my environment. I
believe that single disk approach will be better.

Received on Mon Feb 10 1997 - 08:22:36 MST

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