(r7) SL5UpgradePlanning < LCGTier2

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

%TOC%

---++ Summary sheet

   * [[https://twiki.cern.ch/twiki/bin/view/CMS/SLC5Migration][Central CERN wiki page on the migration and known issues]]
   * Interim consensus for WN model: "SL5, 64bit, gLite v3.2"<br />Important warning of general interest: "dCache client not working on gLite 3.2 SLC5 WN": http://glite.web.cern.ch/glite/packages/R3.2/sl5_x86_64/deployment/glite-WN/glite-WN-known-issues.asp

| *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*  | ?  | ?  | ?  | <p>SL, because of SLC kernel NFS bug </p> |

---++ 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):
<blockquote> 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
</blockquote>

---+++ 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: <br />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 &lsquo;alias&rsquo;), 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.

   * [[%ATTACHURL%/SL5-CMSFacOps20090615.pdf][slides from CMS Facility Operations meeting 2009-06-15]]
   * [[http://indico.cern.ch/conferenceDisplay.py?confId=45476][slides from GDB Meeting 2009-06-10]]

---+++ 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)<br />From: Roland Bernet &lt;bernet@physik.uzh.ch&gt;

[...]

for LHCb:<br /><br /> SL4&lt;-&gt;SL5:    We can run with SL4 and SL5. There is the bug in SL5,<br />                but we have a procedure to run SL4 code on SL5 which<br />                is working.<br />                As we have to move to SL5 anyway, changing to SL5<br />                before startup makes sense.<br /><br /> SL&lt;-&gt;SLC:     We don't care.<br /><br /> 32bit&lt;-&gt;64bit: LHCb will only support 64-bit in the future.<br />                For us is therefore 64-bit a must.