Hi Ben,
Responses inline
On 26 June 2010 10:05, Ben Waugh <[log in to unmask]> wrote:
> Dear All,
>
> This is an appeal for guidance from both those who have put out
> tenders for CPU nodes, and those with knowledge of what makes a good
> worker node for ATLAS in particular.
>
> I know procedures vary between institutions, but I have been advised
> by our Procurement department to do a "mini tender" involving the five
> suppliers who have framework agreements to supply servers to UCL,
> asking for the greatest possible CPU power for a fixed price.
Sounds like a good idea; we did something similar for a ~£17k purchase
at the end of last year.
>
> The HEPSPEC rating is the obvious measure to maximise, but not all
> suppliers have the means or inclination to run a specialised benchmark
> for a relatively small order, about £40k. How have others done this?
> Do you restrict yourselves to the suppliers who already have
> experience in dealing with GridPP and can run HEPSPEC themselves, or
> do you use other benchmarks or some less direct way of comparing the
> CPU rating of the products on offer?
I figure the UCL list includes some of the usual suspects (I see at
least one familiar name ;-) and most of these will have HEPSPEC scores
available. Failing that, you'll have to have a "best guess" at the
performance...or see if anyone's benchmarked similar kit within
GridPP. Of the ~6 suppliers I approached for our purchase last year,
all had HEPSPEC scores available.
>
> There are of course other factors affecting job throughput, including
> hard disks and RAM. Is there some way of measuring the effect of
> these, or would you just set a minimum requirement on both and then
> maximise the HEPSPEC? If you would take the latter approach, what is a
> sensible trade-off between disk performance and price? Presumably
> 10kRPM SAS disks will be better than 7.5kRPM SATA, but maybe a striped
> pair of slow disks would be an alternative? And how much disk space do
> you allow per CPU core?
At Glasgow, we've opted to buy our latest generation of WNs with 2 x
15kRPM disks, and will configure them in a RAID0 array. This followed
extensive testing of various WN configs, using a range of SSDs (X25's
and Kingston Value) versus RAIDED disks. We found the best "bang per
buck" was given by the 2 HDD solution.
>
> If there is anything else I haven't asked but you think I should
> consider, please tell me that too!
Warranty and spares. Make sure you ask for a buffer stock of spare
parts to hold on site. Specifically, you'll want at least one PSU
(they can usually be swapped in seconds without tools), a couple of
hard disks and RAM. If you're feeling adventurous, you might ask for a
spare motherboard too, as a lot of the new systems have hot swappable
system boards.
Cheers
Mike
>
> Best regards,
> Ben
>
> --
> Dr Ben Waugh Tel. +44 (0)20 7679 7223
> Dept of Physics and Astronomy Internal: 37223
> University College London
> London WC1E 6BT
>
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