Subject: Re: CCL:Hardware for modeling

From: Alex Ninaber <[email-masked]>
Date: Tue, 28 Jul 1998 14:33:25 +0100 (BST)

Hi,

To give you another alternative: in the UK DEC 533 computers are currently
sold for 1500 pounds (~1000 dollar). I think you have to buy a cheap PC
monitor with that and some extra ram. It uses Linux as operating system,
so a lot of software should work. If you want DEC Unix it will cost you an
extra 1000 or so (not really worth it, it seems). I think the DEC will
beat the PII233 at least 3-4 times if it comes to number crunching. The
reason why it is so cheap is that Samsung apparently is making very cheap
clone motherboards for the DEC chip. Compusys (or sis?) is selling them
and Annex as well, if you ask for it. Tomorrow we will get our test
machine, if everything is ok, we will buy 8 more and start a farm. Another
thing: I am not sure how well the multiprocessor part is implemented in
Linux. I read the kernel mail digest often, and some problems seem to
occur with it (not always). Also, remember that software is usually not
optimized for a multiprocessor Linux environment, so you probably end up
running two programs, one on each processor (maybe you can solve that with
running MPI on top of it, depending on the program). 

Alex

On Tue, 28 Jul 1998, Marcos Villarreal wrote:

> 
> Hi CCLers.
> 
> I am starting my PhD in Chemistry. I will study Lipid-Protein
> interaccion whit empiricals force fields. We have few
> computer resourses, so we are going to by one computer.
> We have aronud $ 3000 and the way I see, we have two alternatives:
> a) one single procesor Pentium 2 of 400 whit one disk of 9 Gb.
> b) two procesor Pentium 2 of 266 whit two disks of 4 Gb.
> Both  whit 128 Mb RAM and RED HAT Linux. I will be the only one
> using this machine.
> Which one is the best for MM/MD.
>    Thank you very much in advance.
>                                                         
> 
> 
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---

From: Laurence Lavelle <[email-masked]>
Date: Tue, 28 Jul 1998 11:40:47 -0700

Hi Marcos,

If you have a multithread application then dual pentium (new motherboards
should take up to dual PII 450 which leaves room for CPU upgrade when
prices drop).

If you do not have a multithread application but will use the machine at
same time for other applications then MD application will have one CPU and
the other CPU will take care of system overhead (esp. SCSI) and handle any
other application. Or you can run two MD jobs at same time (each will have
about 90% CPU time (although this depends on HD activity)) if RAM is not a
problem. Depends on your run. If your doing only MM/MD then 128MB RAM
should be ok. If you plan on any ab initio don't get any motherboard that
takes less than 512MB. DRAM is now very cheap and you will want to add more.

If you do not have a multithread application and heavy MD runs then go with
PII 400. You want max cache and 100MHz motherboard. 

It is difficult to compare systems without details but my guess is that the
dual 266 is older while PII 400 is newer. That means newer chipset etc.,
better performance all round.

Laurence