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Discussion about the upgrade of WNs to SL(C)5

Summary sheet

Issue ATLAS CMS LHCb Decision
32bit vs 64bit both supported, 64bit preferred 64bit both supported 64bit is a MUST for production
SL4 vs SL5 SL4, SL5 supported with compatibility RPMs SL5 SL4 or SL5 SL5 doable with a "workaround"
SL vs SLC ? ? ?

SL, because of SLC kernel NFS bug

Compatibility libraries

LCG Applications area has published a SL5 Dependency RPM that installs compatibility libraries needed by the application frameworks.

In a message from Claudio Grandi, Nov 13 2009:

Using the gLite 3.2 UI on SL5 currently gives problems in the CMS 
environment because of the mixing of 32-bit (needed by CMS) and 64 bit 
(needed by gLite) libraries. This is being addressed in CMS but for the 
moment only the gLite 3.1 UI is usable in the CMS environment.

VO-specific details

ATLAS

From: Szymon Date: Wed, 17 Jun 2009 10:43:03 +0200

The status of ATLAS software with respect to SLC5 is summarized here: https://twiki.cern.ch/twiki/bin/view/Atlas/PlatformsAndCompilers

From: Szymon Date: Thu, 18 Jun 2009 13:09:38 +0200

Here is some more information from an ATLAS expert (Emil Obreshkov):

In general offline release build on SLC4 should run on SL(C)5 without problems provided that the needed compatibility RPMs are installed together with a proper compiler and also SELinux is disabled or at least "heap exec" is disabled. [...] My impression is that on SL5, SELinux is disabled in which case one will just need to be sure that the needed 32bit compat RPMs are installed as well.

Information about these RPMs can be found here https://twiki.cern.ch/twiki/bin/view/Atlas/RPMCompatSLC5

CMS

CMS has initiated a site poll: https://twiki.cern.ch/twiki/bin/view/CMS/Poll-T1T2-SLC5

From the CMS Facility operations meeting 2009-06-14:
Status of LHC VOs on the topic is that CMS, LHCb and ALICE expect to run SL4 binaries in SL5/64bit systems smoothly, while ATLAS requires to disable (partly) SELinux in order to run in compatibility mode. GDB has to deal with this. There are remaining issues still to be tackled (e.g. distribution of SL4/SL5 compatibility libraries, gcc-4.3 compiler installation - or distribution of runtime libraries), but not very relevant for CMS: we are ready to run SLC5. As long as the experiments primary platform is SL4, the interactive services (e.g. lxplus), Grid UI, build servers need to be maintained (and the ‘alias’), i.e. they do not plan to build/prepare SL4 binaries on SL5 systems. More details here. So, the GDB recommendation to WLCG sites is to start migration after STEP'09. CMS is recommending to all CMS sites to migrate asap, see dates on slides. On CMS constraints from sw, again see slides. The proposal for CMS SLC5 migration at CERN is to migrate asap the T0 and CAF WNs, between CRUSET and CRAFT, i.e. July 5-10. For more details, and testing status, see slides. For constraints from physics, all details in slides.

LHCb

From: Roland Bernet Date: Wed, 17 Jun 2009 13:52:26 +0200

Here the latest of SL(C)5 from LHCb.

We only need 64bit - 32bit will not be supported anymore in LHCb.

About SL5 or SLC5, we never really cared. Until now all our applications did run on SL and SLC.

The main show stopper are the python bindings for the LCG tools (gfal, lfc, lcg_utils) as our whole framework is running in python. Until recently there were no python bindings at all for SLC5 available. They have only just be made available, but tests are reporting systematically "possible memory leaks".

We could try to use slc4 binaries it 32bit is installed, but there is a bug in the compat-ldap 64bit library that prevents dependencies to be solved.

The LHCb application software runs on SL5 and SLC5.

We can only move to SL5/SLC5 when the LCG software problems are solved. No idea how fast they will come up with a fix.

Date: Thu, 10 Sep 2009 10:32:09 +0200 (CEST)
From: Roland Bernet <bernet@physik.uzh.ch>

[...]

for LHCb:

SL4<->SL5: We can run with SL4 and SL5. There is the bug in SL5,
but we have a procedure to run SL4 code on SL5 which
is working.
As we have to move to SL5 anyway, changing to SL5
before startup makes sense.

SL<->SLC: We don't care.

32bit<->64bit: LHCb will only support 64-bit in the future.
For us is therefore 64-bit a must.

UpgradePlanningForm
Title Middleware upgrade
Summary upgrade dCache 1.9.2, SL5 ?
Target Date 02. 07. 2009 ?
Topic attachments
I Attachment History Action Size Date Who Comment
PDFpdf SL5-CMSFacOps20090615.pdf r1 manage 93.7 K 2009-06-18 - 10:02 DerekFeichtinger slides from CMS Facility Operations meeting 20090615
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Topic revision: r9 - 2011-01-21 - PabloFernandez
 
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