Re: Is squid unable to handle the load?

From: Markus Storm <>
Date: Wed, 27 May 1998 09:36:11 +0200

Mark Dabrowski wrote:
> Ok, here's what I've done:
> We have ordered 3 new Adaptec 2940 U2W controllers (UltraWide 2) which go
> 80MB/s, but unfortunately couldn't find anywhere 4GB Ultra Wide 2 drives
> and also BSD 3.1 does not recognize (support) 2940U2W at all ...
> So we ended up installing 2 more 2940 UW's and adding 2 x 4GB drives.

You really don't need fast (Ultra, Wide) or lots of controllers. A single
Fast/Wide one does for us (currently maxing out the CPU at around 30-40
Load distribution is the key. Static (using multiple cache_dirs) is good,
dynamic (which you get when you stripe disks together) is even better.

> The disk configuration of Squid box is 3 AHA 2940 UW controllers and 1 X
> 9GB Drive and 2 X 4.5GB drives. I have defined 3 equal partitions in
> cache_dir, each on each disk.
> Since we just finished installation, i didn't have a chance to make any
> tests, but when the system is almost idle and only 5-10 clients use squid
> there is something weird happening... Every 15-20 seconds I would notice
> number of disk operations/sec jump to about 100 on each disk (which causes
> cpu idle to go down to 100%) and then resumes normally.
> Is squid doing some disk operations every 15-20 seconds? If yes, under
> normal conditions I would not think it can halt the system.... but it
> does... Any ideas?

Assuming you haven't changed your config (in particular cache_mem_low/high),
then most likely UNIX does.
Depending on your UNIX variant (not sure about BSD), part or all of the
or VM cache is flushed to disk.
Try something like running a script doin' while (true) { sync; sleep 2 }.

Received on Wed May 27 1998 - 00:44:48 MDT

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