Re: raising performance

From: Eric Stern <>
Date: Sat, 4 Jul 1998 16:39:58 -0400 (EDT)

On Sat, 4 Jul 1998, Oeschey, Lars wrote:

> Hi,
> since i canīt get a driver for either mylex or compaq raid controllers,
> i have to find some way to get better performance from squid, mainly the
> disk access makes me worry a bit. So I thought about using a second
> machine, putting an additional 100Mbit netcard in borth machines and
> interconnect them via that cards, doing a reound robin DNS to those
> machines and have each other as parent for the other, so they could ask
> for files over the 100Mbit connection.
> Would that work (and help ;)) or do I think wrong there?

IMHO, RAID is not a Good Thing for caches. Write performance tends to be
not optimal on RAID systems, and write performance is critical for caches.
The main benefit of RAID is that it spreads your IO load across multiple
spindles. But, due to the nature of squid's operation, it does this for
your pretty well anyways.

So, skip the RAID and buy lots of hard drives. Get the fastest HDs
available (currently that is the 10,000RPM Seagate Cheetahs I believe).
Get as many as you can. ie if you are planning a 8-9gig cache, get 2 4gig
Cheetahs instead of 1 9gig Cheetah. It costs a bit more, but you'll get
better performance.

If you are looking at ALOT of drives in the cache (say, 8 drives) start
looking into buying multiple SCSI controllers, so you can split the drives
up between the multiple SCSI channels. Seagate claims the Cheetahs can
sustain 20MB/s, so if you are buying Wide UltraSCSI drives, a single
channel can run 80MB/s, so you'll want to put about 4 drives max per SCSI
channel to avoid SCSI bottlenecks.

As for DNS, run DNS servers on each squid box. Configure them to forward
requests to another DNS server running on your network. In this way, if
squid A gets a request, it will resolve the address through your main DNS.
Then, if the same (or similar) request is sent to squid B, it will be able
to get a cached response from your main DNS. Since each squid box will
also cache these lookups, it should keep the load on your main DNS to a

A 100Mbit backbone between the squid boxes is certainly a fine idea. Just
what kind of load are you expecting to handle anyways?

/ Eric Stern - PacketStorm Technologies - (519) 837-0824 /
/ /
/ WebSpeed - a transparent web caching server - available now! /
Received on Sat Jul 04 1998 - 13:49:34 MDT

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