[daip] Re: AIPS on linux

[Eric Greisen]

Shami Chatterjee writes:

 > Well, the old Sparc on my desk has finally been retired, and we got a 
 > dual-Xeon as a replacement. It even came with RedHat 7.3 preinstalled!
 > So I'm doing the ground work for an aips installation, and wanted to run 
 > a few things by you:

      Sounds good.

 > 
 > 1) My gcc version is 2.96, so I realize that I will need to install a 
 > separate gcc 2.95.3 or 3.02. Does the spped advantage of 2.95.3 apply to 
 > Xeon architectures as well? Or, if that is untested, is it expected to 
 > apply? 

    Use 2.95.3.  I will be trying out 3.1 and 3.2 in time but for now
2.95.3 works really well on the PIII dual Xeons we have.

 > 
 > 2) We already have a SOL/SUL aips installation, but the fileserver might 
 > not be the best place to host yet another aips architecture and site.
 > I'm considering a stand-alone installation for this machine. However, I 
 > worry about networked disks and tapes, which I *will* still have to use. 
 > 
 > Any comments on the relative merits of stand-alone vs. adding a different 
 > site and architecture? The install help only tells me "it's really an 
 > advanced topic beyond the scope of this document"...
 > 
 > The SOL/SUL installation is on the MNJ, and so will the Linux machine. 
 > The correct services are already defined in the system-wide NIS map.
 > So it would be nice to share the same AIPS_ROOT. But I can certainly 
 > host it entirely locally... it seems a judgement call, so I'd value your 
 > opinion.

We use a single $AIPS_ROOT with the LINUX and SOL and SUL and SGI
branches populated.  Our HOSTS.LIST file shows 2 sites and we have 2
DADEVS files DADEVS.LIST and DADEVS.LIST.COAOARN.  The former lists
disk areas on Suns, the latter lists disk areas on Linux machines.

You cannot share disks between Suns and Linux machines - the opposite
byte order will cause AIPS to destroy the data of the other
architecture.  You can use disk space on a Sun from Linux (if you can
stand the slow speed) but you cannot share the area.

Tapes may of course be shared.  It really does help to have a single
copy of aips for invoking some of these system-wide services and then
the MNJ need only run CVS once and the 2nd machine can run a secondary
sort of job.

As you add more Linux boxes at your site you will find that a
stand-alone gets harder to maintain.  But we have a good file server
machine that hosts the actual files and that makes a real difference.
Having Linux separate from a slow Sun server may well be preferable.

In other words, the difference is not all that clear cut - even the
MNJ is fairly simple now with CVS and not much of a load on us.

Eric Greisen