Re: [squid-users] access to cache is very high

nyoman karna wrote:
> guys,
>
> I've been using squid for 5 years in my educational institution
> (IM Telkom - Telkom Institute of Management)
> but this is the first time i encounter this problem.
> need your expertise.
>
> I'm using HP Proliant ML110 G5 with 320GB of SATA disk.
>
> I'm using squid 2.6 stable 16 (FreeBSD 6.3) with 100GB of squid-cache.
> when the cache was not yet full, there's no problem whatsoever
> but when the cache is full (but still 90% of the mountpoint),
> squid is always busy validating its objects
> and refusing all client connection.
>
> this is part of file /usr/local/etc/squid/squid.conf
> ------------------------------------------------
> maximum_object_size 16384 KB
> minimum_object_size 0 KB
> maximum_object_size_in_memory 8 KB
> cache_replacement_policy lru
> memory_replacement_policy lru
> cache_dir ufs /webcache 100000 64 256
>
> this is the capture when the squid refusing connection
> -------------- (using top) ----------------------------------
> CPU states: 39.5% user, 0.0% nice, 55.3% system, 5.3% interrupt, 0.0% idle
> PID USERNAME THR PRI NICE SIZE RES STATE TIME WCPU COMMAND
> 77059 squid 1 123 0 186M 184M RUN 0:10 86.26% squid
>
> -------------- (using systat) ----------------------------------
> /0% /10 /20 /30 /40 /50 /60 /70
> ad4 MB/sXXXXX
> tps|XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
>
> -------------- (cache.log) ----------------------------------
> 2009/03/20 09:54:44| httpAccept: FD 11: accept failure: (53) Software caused connection abort
>
>

UFS as the slowest IO process in Squid, is not the best for large
caches. Since you are on FreeBSD try diskd instead. No change of cache
is needed to alter ufs->diskd as the storage manager type.

Average HTTP object size these days is between 64KB and 128 KB. Your max
in-memory size of 8KB is causing a lot of objects to be disk-saved
without need.

Also check the garbage collection range you have set:
http://www.squid-cache.org/Doc/config/cache_swap_low/
http://www.squid-cache.org/Doc/config/cache_swap_high/

Amos

-- 
Please be using
   Current Stable Squid 2.7.STABLE6 or 3.0.STABLE13
   Current Beta Squid 3.1.0.6