|
SLC4 has been
certified by the
Linux Team at CERN, in May 2006, and the default LXPLUS OS will
be SLC4 on 64 bit by 19.01.2007 8:30am.
LXPLUS running SLC4
We have set up new LXPLUS nodes to run SLC4 on 64 bit (x86_64),
and some LXBATCH capacity as well.
More batch capacity will be moved from SLC3 to SLC4 on demand of
the experiments and when the GRID middleware has been released in
production on SLC4 as well. currently, our SLC4 WN are available in
the SLC4 preproduction system at CERN, and via local queues.
These LXPLUS nodes are also available behind the load balanced
alias:
lx64slc4.cern.ch
(For cross checks, we still have a handful of machines running
SLC4 32 bit (i386). To go to those on LXPLUS, login to
lx32slc4.cern.ch)
Both names are DNS aliases, and they point you to a least loaded
machine for that platform. As mentioned above, it is planned to change the default
alias:
lxplus.cern.ch
to point to lx64slc4.cern.ch by the 29.01.2007 (8:30 am).
LXBATCH running SLC4
To use the LXBATCH capacity on SLC4, you simply submit from the
corresponding LXPLUS nodes, and you will end up on the right
architecture. Cross submission is still under investigation.
As usual, this behavior is steered by the 'TYPE' resource, which is
SLC4_64 for the new SLC4 architecture on 64 bit. (For i386 on SLC4
it is SLC4)
Running SLC3 and SLC4 32 bit (i386) code on SLC4 on 64 bit
(x86_64)
We have installed the so called 'compatibility libraries'
on our SLC4 x86_64 LXPLUS and LXBATCH nodes, which allow to run and
compile 32 bit applications on 64 bit. The idea is that we provide
SLC4 on a 64 bit OS, and it should be possible to run 32 bit
applications as well as 64 bit applications on these machines. In
addition, many of the 32 bit SLC3 application will work as well.
This is also the way how many applications, including e.g.
CERNLIB and the GRID middleware, will run, at least in the
beginning, on our SLC4 machines.
Cross compiling 32bit code on lxplus
For some libraries there are no 64bit versions available
yet. An example is CERNLIB, but this may also be true for some
experiment software libraries, in particular LEP.
If you get messages like "skipping
incompatible library ..."
while compiling your code on lxplus, then it's most likely that you
are trying to mix 64bit and 32bit code which does not work. If it is
not possible to recreate the offending library in 64bit, you attempt
to create 32bit code. The way out is to create your code on native
32bit SLC4 machines (lx32slc4.cern.ch or lx32slc3.cern.ch), but you
also have the possibility to directly create 32bit code on 64bit
machines.
To compile 32bit code on 64bit machines using the GNU (gcc/g77/g++)
compilers you have to add the -m32 flag
to the compile/link options. If you are using a different compiler
please check the documentation. Many of them support similar
options.
For ex. the Lahey "lf95" needs the
extra flag: -Wa,--32
Problem report
As usual, we have set up a mailing list to report problems,
suggestions and feedback you have for these new platforms:
it-dep-fio-lxslc4@cern.ch
Before you report a problem to this list, we kindly
ask you to check these two points first:
Known problems with CERN Linux SLC4
-
Has your problem already been reported to the
mailing list mentioned above? For this, you can check our 'known
problem' page, that we have set up to trace reported problems. You
can find that page at:
Known issues with SLC4 on
LXPLUS and LXBATCH
Next Steps:
-
Make the GRID UI available for SLC4 on AFS
-
Put the gLite WN middleware on LXBATCH/SLC4 into
production
-
Migrate the experiment shares on LXBATCH to SLC4
|
