Re: cache layout questions (& disaster recovery!)

Julian Richardson:
>
> Hi all,
>
> Our linux squid proxy's been running here quite happily for the last
> week or so, so it's time to format the old MS proxy machine and migrate
> squid over to that and give it some decent hardware in which to run...
>
> The machine's got two 9GB SCSI disks in it. Now, I'd expect it's better
> to put the core OS, swap, binaries etc on one disk and the cache on the
> other for performance reasons. What about the logs though? Any idea if
> it's better to have those on the OS disk or the cache disk, given that
> they'll generate a disk access of their own fairly often?

According to the squid FAQ it is much better to spread cache directories
over several physical disks and even the controllers (!). If you think
seriously about the performance, it is most effective way to improve it.
If you have dedicated machine to squid, don't worry about the logs and
system software - it takes much less than you currently expect. Turn on
log buffering, turn off logging icp queries, fqdn of clients and ident
lookups and your on good way to beat squid's speed records ;) You can
 Except that you could:
 - raise squid process priority during startup by starting it with command:
   "nice -j -20 /usr/local/squid/bin/squid -Y"
   suppressing -s option (logging to syslog) is also good for performance ;)
 - lower users process priorities using available mechanisms,
 - recompile linux kernel as small as possible only with absolutely
   necessary drivers (the rest can be done as modules),
 - deal with hdparm command to improve disk performance.
 - set up carefully your proxy configuration files and directives for
   direct fetches for caching only necessary objects (not these accessible
   fast with direct fetch - e.g. local network!).
 - use a plenty of RAM for squid - this will reduce the number of the disk
   reads and speed up the transfer to the clients.

   I watch my installation with my custom-made perl script (which - I hope -
I will soon give available to the public). This helps me a lot tuning squid,
choosing the best siblings and parents (in fact the route), refresh patterns,
watch the speed of different fetch combinations. The deals described above
improved signiffically the performance of my squid server... I could wrote
a book about that ;)

Regards,
Maciej

-- 
           Maciej Kozinski         http://www.uck.uni.torun.pl/~maciek/ 
	   Remember: Un*x _IS_ user friendly... It's just selective about
		     who it's friends are.