Date: Tue, 15 Jul 2008 05:51:50 -0300 (BRT)
> 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.
>>
and the whole issue again and again is understated, at least you guys admit
already
dualcores ...
I really do not understand the resistance, there *_IS_NO_* doubth that an 8core
machine is faster than a twocore - and whatever software you put in there it
*_IS_*
faster, unless it's idle what eventually is the problem at all, are your
machines
idle so you don't see it ????
of course the budget IS a point (8core is expensive) but a AM2 quadcore is
absolutely cheap today so there is again NO doubth what kind of CPU to buy,
especially squid takes advantage of quads, especially of AMD quads what I
believe
cause of it's NUMA arquitecture
in order to show it once I attach 3 images of Average load comparism, and
please,
before flaming this up try to understand what Unix load average really means and
say, I graph it directly to the available cores so you can see when spikes
are high
and continuously near or above CPU than the machine can be seen as busy, so when
spikes are low machine is free to breath (less IO wait-state) and to serve of
course
so then, less your load average more response time you get, and as I ever
said: You
can feel it and that is what the connected clients spell as "fast"
so you can see a AM2 X2, a AM2 X4 and a Dual opteron dualcore machine, both AM2
sockets are with constant 6-8MB through-going traffic, the opteron serves
16MB, all
three have 3 SCSI-U320 250G disks on ZFS and a 16G for the OS, both AM2 are
with 4G
and the opteron with 16G of RAM, each of them with 5 ETHs with 4 internal
subnets
and one external, transparent proxy running three squid instances and diskd,
firewall and some scripts collecting stats and making rrdtool images, the AMS
serve
about 450 and the opteron 800 clients at peak hours, average of 250kbit/s of
download limit each and not to forget, this is freebsd 7-stable amd64
so my suggestion is get yourself an as-much-cores you can get and enjoy
michel
I send two more msgs with the next images attached, this is the 2x dualcore opteron
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