NIS?

Nordwall, Douglas J Nordwall at pnl.gov
Fri Oct 5 10:52:52 EDT 2001


Tim and myself will get to experience a larger cluster here in not too long. A
64 node jobbie. We'll run appropriate tests on it as well (as well as doing some
benchmarking aka seti at home :)

> -----Original Message-----
> From: Robert G. Brown [mailto:rgb at phy.duke.edu]
> Sent: Friday, October 05, 2001 4:48 AM
> To: Tim Carlson
> Cc: Greg Lindahl; beolist
> Subject: Re: NIS?
> 
> 
> On Thu, 4 Oct 2001, Tim Carlson wrote:
> 
> > On Thu, 4 Oct 2001, Greg Lindahl wrote:
> >
> > > Don Becker gave some good reasons why NIS isn't used by most big
> > > clusters. The investment bank I used to work for (5 years 
> ago) made
> > > every machine a slave in order to avoid NIS's braindamage.
> > >
> >
> > Before bashing NIS completely, maybe a qualifier of "sucks on Linux"
> > would be appropriate? I ran NIS with one master and 50 
> slaves in a Solaris
> > environment (2.5 -> 2.8) for 5 years and can't think of one problem
> > (outside the time we tried to add a slave and did it incorrectly).
> >
> > Ran NIS on a 32 node Linux cluster based on RedHat 6.2 for six
> > months and never had a problem with NIS.
> 
> We actually run NIS in the physics department, partly because 
> we've been
> doing so continuously since sometime in the mid-to-late eighties.  We
> started on SunOS, migrated to Solaris (linux servers just 
> didn't work at
> the time) and some years ago migrated to linux only -- we have pretty
> much a straight linux operation at this point with the usual exception
> of the half dozen WinXX systems that we don't take care of and a
> selection of lab and classroom NT systems that we have to run 
> to be able
> to use certain physics/teaching software.  NIS certainly works "well
> enough" in a linux-only departmental environment (up to 
> several hundred
> users and machines).
> 
> However, I agree that NIS sucks for the reasons Don gave on a true
> beowulfish cluster.  A lot of overhead and a resource bottleneck.
> Remember, if a system is stat'ing a lot of files it 
> continuously has to
> go back and check access permissions, which typically involves an NIS
> hit.  On the other hand, it does make managing users in a midsized
> organization easier and generally works pretty well.  So if you are
> building a cluster to do embarrassingly parallel long running compute
> jobs (so you are unlikely to encounter the contention problems Don
> described) NIS is a perfectly reasonable way to manage user accounts.
> 
> Unfortunately, we are pretty darned certain that NIS leaks 
> memory; if it
> runs a "long time" it tends to crash, and can easily drag down clients
> in mid-query with it.  So it also sucks because it is somewhat broken,
> at least compared to the tremendous stability of most of the core OS
> services.  I believe Seth (our systems guy) has NIS servers 
> restart once
> a day to clear their memory allocation to avoid this problem.
> 
> NIS is old and should almost certainly be thoroughly 
> redesigned.  We may
> one day transition to LDAP for directory services but in the meantime
> NIS or SOME sort of distributed database service is in my opinion
> necessary in order to manage a midsize organization (although it is
> generally NOT necessary to manage a cluster with only a few, slowly
> varying users).  E.g.  rsyncing /etc/passwd doesn't scale 
> very well when
> you have 100's of users moving freely from machine to machine among
> 100's of machines, although of course one can work very hard and build
> decent enough scripts to avoid some of the problems.  In 
> fact, kludging
> together one-of-a-kind (nonportable) solutions to problems 
> like this is
> the very definition of things that don't scale well and are generally
> "bad ideas" in systems administration.  It is heartening that 
> the Scyld
> folks are working on a truly lightweight replacement -- one can only
> hope that it is portable back to mainstream linux.
> 
>    rgb
> 
> >
> > Tim
> >
> > Tim Carlson
> > Voice: (509) 376-0300
> > Email: Tim.Carlson at pnl.gov
> > EMSL UNIX System Support
> >
> >
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> 
> -- 
> Robert G. Brown	                       
> http://www.phy.duke.edu/~rgb/
> Duke University Dept. of Physics, Box 90305
> Durham, N.C. 27708-0305
> Phone: 1-919-660-2567  Fax: 919-660-2525     email:rgb at phy.duke.edu
> 
> 
> 
> 
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