RE: [SQU] Squid with muliple disks or hardware stripping...

From: OptiDynamic Squid Admin <squid@dont-contact.us>
Date: Sat, 2 Sep 2000 10:41:22 -0400

Yes multiple disks give a considerable performance increase to squid,
however RAID-0 is questionable. This is because RAID-0 is primarily designed
for large synchronous reads and writes, which squid does not do. Your will
get much better performance with 3 disks all mounted separately than 3 disks
in any RAID configuration. squid's load balancing for multiple disk is
excellent, for example look at my "df -m" output:

Filesystem 1M-blocks Used Available Use% Mounted on
/dev/sda1 1634 1193 356 77% /
/dev/sdb1 8539 6796 1744 80%
/usr/local/squid/cache1
/dev/sdc1 8539 6787 1752 79%
/usr/local/squid/cache2
/dev/sdd1 8539 6790 1749 80%
/usr/local/squid/cache3

another thing to consider is when you have a drive fail under RAID-0 is
cache is gone and you loose uptime. however, with multiple mounts you just
simply take the line for that drive out of config, send squid a rehash,
unmount drive and then remove it (if you have hotswap like I do) and then
put in new drive, then remount, then squid -z to recreate swap directories
and then add that drive back to config and rehash. no uptime lost and squid
rebuilds the other drive rather quickly.

As to the other question, the defaults are to optimize file system
performance, changing these values on a standard file system such as ext2
will just cause your performance to suffer.

John

-----Original Message-----
From: George Dimitriadis [mailto:dimitria@forthnet.gr]
Sent: Saturday, September 02, 2000 9:30 AM
To: squid-users@ircache.net
Subject: [SQU] Squid with muliple disks or hardware stripping...

According to the squid polygraph benchmark, squid performs better with
multiple
disks. In case that we have the option to combine multiple disks with
stripping
using a hardware RAID controller, is this preferred over the multiple disk
configuration for squid ?

Another question is how many first-level and second level directories to
create
for each disk in respect with the cache size ?

Any help would be appreciated ...

George D.

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Received on Sat Sep 02 2000 - 08:40:50 MDT

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