[rescue] Cray J90s

Joshua D. Boyd rescue at sunhelp.org
Tue Jun 12 16:38:31 CDT 2001

On Mon, 11 Jun 2001, Zach Malone wrote:

> Hello,
>     This list seems to be a little more varied in types of hardware then I thought it would be when I joined the list, however, I noticed that some people have posted crays up for sale on eBay, no real steals though.
> http://cgi.ebay.com/aw-cgi/eBayISAPI.dll?ViewItem&item=1245498968
> http://cgi.ebay.com/aw-cgi/eBayISAPI.dll?ViewItem&item=1244448223
> They are both J90s though, and at those prices, a dual Athlon system will exceed them in gigflops per dollar, and total gigaflops.  (Two 1.4ghz Athlons would get you about 4 gigaflops).

A stack of Athlons would be cheaper, and given enough of them, for some
tasks you might get better performance.

But keep in mind that things are not always what they seem.  For instance,
a G4 Cube can in theory crank out 2giga-flops, but closer inspection
reveals that the G4 cube only has something like 800m/s of memory
bandwidth compared to over 2g/s for athon tbirds.  

Likewise, these Cray's would have much higher bandwidth up and down the
board compared to the Athlons.  Sure, under extremely limited ideal
circumstances Athlons can match this thing, but for most tasks, the Cray
will be faster.

But then, if you task is something that works well on mosix or other
cluster systems, then for the ammount of money that the Cray costs to
operate over a year, you could probably build a faster cluster.

Anyway, the real reason to buy a J90 is the coolness factor.

Joshua Boyd

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