smp or uni for file server

[James Wilkinson]

mal wrote:
> Does any one know if there are figures for this anywhere
> I was wondering if having 2 processors makes a
> lot of difference in a machine that is just a file server

Depends. Are you doing "live" virus-scanning (as data is written and
read)? Is the box doing anything else?

If you want to do "live" virus-scanning, then you should go to the
project / supplier to find out how much processor time it takes. (If
you're serving a lot of .zip files or, worse, .tar.bz2 files, and expect
to look inside to check that you aren't serving up a virus each time you
serve the file, then yes, you will need a lot of processor power.

The other thing to consider is TCP/IP overhead. As I understand things,
without hardware assist, you can expect to use the equivalent of a 1 GHz
processor (*very* roughly) to do TCP/IP checksums and the rest of the
suite at a sustained 1 Gbit/s.

On the other hand, you'll need at least RAID 5 to get that speed out of
SATA hard disks (and if you *are* using software RAID 5, don't forget to
count in the processor overhead for that).

On the third hand, you can get cards that will do hardware RAID 5 (for
example, 3ware or Adaptec SCSI), and you can get Ethernet cards that do
checksum offload (they'll do the checksums in hardware, taking the load
off the CPU). This might be a lot more cost-efficient for you.

If you're using 100 Mbit/s Ethernet, forget it. That will be the
bottleneck.

Finally, note that both Intel and AMD have recently come out with
"dual-core" processors: effectively two CPUs in one package. These might
be a lot more economical for you.

Hope this helps,

James.

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