Why not NT clusters? Need arguments. 10/7, 10:43

Jeff Layton laytonjb at mindspring.com
Sun Oct 8 07:18:25 PDT 2000

At 10:43 PM 10/7/00 +0800, you wrote:
>Jeff :
>Cornell's AC3 is a NT cluster which is a production running horse,
>you may find further details from them such as MTBF, MTTR for RAS !
>I would like to see both NT and Linux coexist !
>What's you definitionof memory leak ?


   I had a friend who ran some tests on Windows NT 4.0 who found
that opening and closing applications on NT left memory unreleased.
I think of this as a memory leak. In addition, I think you can
several article on the web about this as well.
   Of course, I'm sure there are parts of Linux that have the same
thing, but I haven't done any testing nore have I seen any
articles on it on the web.
   As another example, at Lockheed we have several LARGE NT machines
that we use for general use (mostly MS Office) and MS fileservers.
After about 18 months of continues usages, the sys-admins have had
to resort to rebooting ALL of the boxes every single night to clear
problems. They have spoken with MS about the machines at length
(the old sys-admin lived on the phone to MS - his words, not
mine) but with no resolution. Rebooting the boxes seems to be the
only solution they came up with.
   Don't get me wrong. I use NT a fair amount at work for various
things. I LIKE Word, etc (I guess that makes me a heretic in the
Linux world), although PowerPoint can be very frustrating and
Access while a good cheap DB (expecially compared to something
like Oracle which is $$$$) has some problems as well. In addition,
no matter how many times I offer, my family won't convert to Linux
from Win98. I do like the multimedia stuff in Win98 and found it
to be much better than anything in Linux.



>David C. Wan
>10/7, 10:43
>Jeff Layton wrote:
>> At 08:31 PM 10/6/00 -0400, you wrote:
>> >On Fri, 6 Oct 2000, Jon Tegner wrote:
>> >
>> >> In a disussion of clusters I got the question why not using systems
>> >> running microsoft NT. I only came up with cost and stability in a
>> >> sweeping way, and I couldnt present more quantitative arguments. Later,
>> >> I even found that an nt cluster sits on place 207 on the top500 list
>> >> (see http://www.top500.org/lists/TOP500List.php3?Y=2000&M=06)
>> >> is that an exception, or are there many of these beasts around?
>> >>
>> >> I would appreciate to be enlightened on this issue.
>> >
>> >
>> >The fine people on this list can provide a large number of reasons
>> >for choosing Linux over NT. Let me give you an empirical observation.
>> >
>> >I have not read about or seen any reference many production
>> >NT clusters. (Those that are actually doing something useful)
>> >On the other hand, I can tell you we have quite a few customers who
>> >are designing aircraft, computing molecules, and finding oil
>> >with Linux clusters.  There are many other applications out
>> >there running day in and day out on Linux clusters. I have not
>> >seen this with NT. My only conclusion is that if it worked
>> >well you would see more. One sure reason is that HPC (High Performance
>> >Computing) has been and will continue to be a *NIX world. Just
>> >seems to work better.
>> I can add an anecdote, but I can't name the particular site.
>> One site that I've worked with (not mine) has a 64 processor
>> Linux cluster and a cluster with about 32 processor NT
>> cluster. When I spoke with the sys-admin of the Linux cluster
>> they told me that the longest the NT cluster had stayed up
>> for a run was 4 HOURS. On the clusters I run at work (Lockheed-Martin)
>> our runs are at least 30 hours. Consequently, a 4 hour uptime
>> for a cluster is absolutely unacceptable even if we save
>> intermediate results and restart the codes (CFD codes).
>> In addition, the sys-admin was telling me that during a
>> run (using MPI) if a node failed, the WHOLE cluster came
>> unglued and all the nodes had to be rebooted! Not a pretty
>> picture.
>> This was last year (1999). I'm not sure what's up in 2000,
>> but I don't think it would be near the stability of a Linux
>> cluster. I think the MPI/Pro guys have done some good things
>> to help reduce the problems on NT clusters, but I don't think
>> they can cure the unstable OS (with SEVERE memory leaks).
>> Perhaps Windows 2000 at Cornell is better than NT, but I'm
>> not betting on it (has anybody checked 2000 for memory leaks
>> yet?).
>> Good Luck,
>> Jeff Layton
>> Lockheed-Martin
>> >
>> >Doug
>> >
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