Re: [SQU] Hardware RAID0 or 2 independ disks

Joe Cooper wrote:
>
> > I am going to add 2 disks.
> > I have 2 solutions :
> > 1) Using my RAID external controller (Mylex DAC960SX), I put the disks
> > in raid0, so I shoud have high performance
> >
> > 2) Using my RAID controller, I can put the 2 disks in independant, so I
> > configure 2 different cache_dir
> >
> > You must know that I can't use disks outside my raid controller...
> >
> > What is the best for high performance and increased load (should be more
> > than 50 requests/s in a few months) ?
> >
> > Thanks in advance for your help !
>
> 50 requests/s is easy on even a non-async compile of Squid (we get more
> than that from , and adding a couple more SCSI disks will only increase
> your performance (assuming you don't go into swap...so lower your
> cache_mem to 64MB, probably).
>
> Either RAID 0 or separate cache_dirs will be fine for your workloads,
> although I usually go with more traditional controllers and separate
> cache_dirs. The performance difference would be felt if you were
> hitting your cache harder than 50/s, because with striping you have
> parity time and you're chopping up very small files (average 11k
> probably) into potentially smaller chunks (8k, probably)...you end up
> having the latency of the slowest disk that has a piece of the file on
> every request rather than the latency of a single disk. Because of
> this, since you have a choice, go with separate cache_dirs. You'll
> still get the benefit of the big RAM cache on your Mylex, and none of
> the negatives of striped disks.
>
> There will probably come a time when Squid uses larges block writes and
> reads, and striped disks will probably work great at that point, but
> until then it's probably most effective to avoid them.

Ok ! I think I am going to follow your advice...
Thanks a lot for your very precise and technical response :)

Just one question :
If one disk crash, will squid fail ?

-------------
Fabien SALVI Centre de Ressources Informatiques
                  Archamps, France -- http://www.cri74.org
                  PingOO GNU/linux distribution : http://www.pingoo.org

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