CCL: W:hardware for computational chemistry calculations

 Sent to CCL by: "Perry E. Metzger" [perry]![]
 "Igor Filippov Contr igorf[]"
 <> writes:
 > Sent to CCL by: "Igor Filippov [Contr]" [igorf|*|]
 > Excellent advice. I would agree with everything, except for the "buy
 > Dell" part. If you've bought Dell (and probably any other named brand
 > PC) - be prepared that it won't be upgradable,
 Well, do the economics. It isn't worth upgrading machines any
 more. Generally after a couple of years you need to replace
 effectively everything in order to upgrade.
 My usual advice to an organization is to assume that machines should
 be cycled out very fast. You are better off (if you're doing high end
 computation) buying fewer, cheaper and slower machines and replacing
 them all every year than buying more ultra-fast boxes every three or
 Why? The fastest possible boxes are usually very poor
 price/performance -- you can pay 50% more for only a few percent extra
 oompfh. If you're doing parallel computation anyway, you really only
 care about cycles per second across the cluster per dollar, not cycles
 per second per box.
 If you set an annual budget, and buy and replace portions of your
 compute cluster every year (or turn last year's compute cluster into
 the "lower end" cluster every year until you run out of room/power and
 get rid of them), you will never have as fast a cluster as your
 neighbor in year one, but he'll be way envious of you in year three
 when his machines are maybe a factor of 6 slower than yours. I suggest
 that organizations budget what they are willing to spend annually on
 their compute cluster and go for the best price/performance boxes each
 year in the quantity they can afford. Next year's machines will do
 twice as well for you, and you will be able to buy them next year
 instead of waiting three years.
 Of course, doing the math yourself is advisable. The exact time
 frames, difference in price/performance between the top and not quite
 top end machines, etc. shift very fast. My only point is, keep in mind
 that computers are not forever, and Moore's Law is an exponential
 curve, so given that you're going to replace them eventually anyway,
 try to treat them more disposably.
 > and after this particular model goes out of fashion it won't be
 > repairable either.
 Dell does pretty well on repairs during their couple year repair
 period. After that, you should probably replace if you're using the
 box for compute bound work.
 > Their cases are a nightmare to disassemble
 As I said, though, if I was buying more than 2 or 3 boxes (or if I was
 buying 2 or three high end AMD64 boxes) I wouldn't buy Dell any
 more. If you only have that many boxes, however, you might as well let
 the Dell people service the machine -- you can't afford enough spare
 parts on hand yourself anyway.
 I have to say, though, I have a bunch of Dells and their 1U and 2U
 boxes seem just fine to me in terms of ease of disassembly. Two
 thumbscrews and the lid just comes up. If you're talking about
 non-rack mountable cases, well, I don't buy those for servers or
 compute farms. Maybe they are a nightmare, but I don't buy 'em so I
 don't see 'em.
 > I would suggest buying things from a small-time vendor that:
 > a) uses only non-proprietary components - i.e. case, power supply, etc.
 > that you can get at any CompUSA or BestBuy if you ever need to replace
 > them.
 The principle is reasonable, but you'll never get power supplies
 etc. that will fit in rack mount cases at CompUSA. They simply don't
 sell them. I usually get stuff like that online from NewEgg.
 > This way you'll get exactly what you designed yourself and you'll be
 > able to repair/upgrade/modify it by using a simple Philips screwdriver
 > and parts that you can get at any computer store. And it will be cheaper
 > too - I'm more than a little surprised about the talk about "cheap
 > prices at Dell" - go to you can find tonnes of places
 > with better deals, where you don't have to pay for the "Dell"
 sticker on
 > your computer case.
 Last year, I was looking for a pair of new 1U servers. I got a couple
 > from Dell for $700 each. None of the white box guys would sell me
 identically configured for less than $900. Now, I didn't buy the
 memory from Dell -- they squeeze you for all they can on that (how do
 you think they sell the base systems so cheap?), and so I always buy
 > from Crucial instead -- but the boxes themselves were unbeatable.
 Right now they're selling deskside boxes with amazing configs for like
 $300, which for a poor chem department that could not afford better
 would be a steal.
 BTW, keep in mind, I do *NOT* advise buying Dell if you're getting
 anything in quantity or anything "serious" and keep in mind that they
 do NOT do AMD64 stuff, so if you need better than bottom end, you
 can't buy from them anyway. Mostly I recommend them to people who need
 a good $300 or $800 box, can't do the maintenance work themselves and
 don't want the fuss.
 Perry E. Metzger