Hi,
One thing to keep in mind is that in my experience, it makes sense to
not only get fast disks, but put as much RAM in the box you can
afford. Now *don't* give this all the squid via the mem_cache config;
let the OS use the spare memory for caching disk reads. This will spee
Additionally, don't RAID your disks beyond RAID 1, and only do that if
you have to for reliability requirements. The more individual spindles
attached to separate cache_dirs, the better. Amos is right that I/O
trumps CPU here every time.
When we swapped out older squid boxes that couldn't take more than 2GB
of RAM, or more than one disk, and put in 64-bit boxen with 32GB and 3
cache-dirs (6 drives, paired into three RAID1 devices), we saw things
improve dramatically despite the fact that the CPUs were actually
slower. We went from topping out at 5K queries per minute to being
able to handle ~20K/minute without breaking a sweat. Pretty dramatic
IMHO.
Hope this helps,
-Chris
On Jul 14, 2008, at 10:04 AM, Amos Jeffries wrote:
Anna Jonna Armannsdottir wrote:
On mán, 2008-07-14 at 13:01 +0200, Angelo Hongens wrote:
All the servers I usually buy have either one or two quad core
cpu's,
so it's more the question: will 8 cores perform better than 4?
If not, I would be wiser to buy a single Xeon X5460 or so, instead
of
2 lower clocked cpu's, right?
In that case we are fine tuning the CPU power and if there are 8
cores in a Squid server, I would think that at least half of them
would
produce idle heat: An extra load for the cooling system. As You point
out, the CPU speed is probably important for the part of Squid that
does
not use threading or separate process. But the real bottlenecks are
in the I/O, both RAM and DISK. So if I was buying HW now, I would
mostly be looking at I/O speed and very little at
CPU speed. SCSI disks with large buffers are preferable, and if
SCSI is not a viable choice, use the fastest SATA disks you can
find - Western
Digital Raptor used to be the fastest SATA disk, dot't know what is
the
fastest SATA disk now.
This whole issue comes up every few weeks.
The last consensus reached was dual-core on a squid dedicated
machine. One for squid, one for everything else. With a few GB of
RAM and fast SATA drives. aufs for Linux. diskd for BSD variants.
With many spindles preferred over large disk space (2x 100GB instead
of 1x 200GB).
The old rule-of-thumb memory usage mentioned earlier (10MB/GB +
something for 64-buts) still holds true. The more available the
larger the in-memory cache can be, and that is still where squid
gets its best cache speeds on general web traffic.
Exact tunings are budget dependent.
Amos
--
Please use Squid 2.7.STABLE3 or 3.0.STABLE7
