CERN IT Department CH-1211 Genève 23 Switzerland t SL(C) 5 Migration at CERN CHEP 2009, Prague Ulrich SCHWICKERATH Ricardo SILVA CERN, IT-FIO-FS

CERN IT Department CH-1211 Genève 23 Switzerland t What will be covered? Motivation –Context and lifecycle –Software –Hardware Opportunities Issues Current status Plans for the future Conclusions SL(C) 5 Migration at CERN - 2

CERN IT Department CH-1211 Genève 23 Switzerland t Motivation – Context and lifecycle (1) SL(C) 5 Migration at CERN - 3 RHEL 4 (Feb Feb 2009*) ▼ SL 4 (Apr Oct 2010) ▼ SLC 4 SLF 4 RHEL 5 (Mar Mar 2011*) ▼ SL 5 (May (?)) ▼ SLC 5 SLF 5 * (End of Production 1 Phase)

CERN IT Department CH-1211 Genève 23 Switzerland t Motivation – Context and lifecycle (2) We want stability during the LHC run period! SL(C) 5 Migration at CERN SLC 5 LHC SLC 4

CERN IT Department CH-1211 Genève 23 Switzerland t Motivation – Software (1) Newer versions of software which include new features and bug fixes are not available for SL(C) 4 –Bug fixes and increased performance in the XFS code Security –Some security fixes need to be back-ported to our versions of the software Virtualization support –No support for virtualization tools in SL(C)4 –We want to increase the use of VMs for consolidation of resources SL(C) 5 Migration at CERN - 5

CERN IT Department CH-1211 Genève 23 Switzerland t Motivation – Software (2) New compiler –gcc-4.1 is the default system compiler for SL(C) 5 –the Architects Forum selected gcc as the official compiler for SLC5 gcc is in SL(C) 5.3 –We expect significant performance increases with compiler support for new architectures SL(C) 5 Migration at CERN - 6

CERN IT Department CH-1211 Genève 23 Switzerland t Motivation – Hardware Performance Power saving features Hardware drivers Virtualization features of newer CPUs Support for new CPU architectures –AMD Shanghai CPUs –INTEL Nehalem CPUs SL(C) 5 Migration at CERN - 7

CERN IT Department CH-1211 Genève 23 Switzerland t Opportunities Changing the operating system enables us to deploy other major changes internally New tools for management of large clusters –Improved user management (ldap based) –New service oriented, name space approach for our internal fabric management tools (Quattor / CDB) Security –SElinux enabled by default –Run monitoring agents under a non privileged account (Lemon) SL(C) 5 Migration at CERN - 8

CERN IT Department CH-1211 Genève 23 Switzerland t Issues (1) We need to keep backwards compatibility with 32 bit SLC4 –Code compiled on 32 bit SLC4 must be able to run on SLC5 –Experiments have lots of code which won’t be ported soon –In some extreme cases only binaries exist SL(C) 5 Migration at CERN - 9

CERN IT Department CH-1211 Genève 23 Switzerland t Issues (2) Change of lxplus (interactive cluster) alias –Until this switch is done code is compiled on SLC4; after that point software will by default be compiled on SLC5 –Should happen once the majority of the resources are migrated on WLCG –All the VOs are confident they can move to SLC5 by the summer SL(C) 5 Migration at CERN - 10

CERN IT Department CH-1211 Genève 23 Switzerland t Current status Fabric management tools ported to SLC5 –Installation –Monitoring –New user management system in place 10% of existing worker node capacity is on SLC5 –Behind 4 CEs (2 LCG + 2 CREAM) –SL5 WN software was released yesterday (23 rd of March) Ramping up of the interactive cluster (lxplus) as demand increases SL(C) 5 Migration at CERN - 11

CERN IT Department CH-1211 Genève 23 Switzerland t Future plans (1) Move CASTOR disk servers to SLC5 Move GRID services to SLC5 –As the software is released into production –UI in the horizon Interactive Linux cluster (lxplus) alias switch is being discussed with the VOs SL(C) 5 Migration at CERN - 12

CERN IT Department CH-1211 Genève 23 Switzerland t Future plans (2) All pledged CPU capacity for the LHC experiments for 2009 will be on SLC5 by the summer –SLC4 resources will be kept for other user communities at CERN –No “big bang” approach SL(C) 5 Migration at CERN - 13

CERN IT Department CH-1211 Genève 23 Switzerland t Conclusions Move to SLC5 as main operating system well ahead of data taking –GDB: “Every experiment is interested on a transition to SLC5/64bit of the Grid resources as soon and as short as possible.” CERN has been providing SLC5 resources for several months Close collaboration with the experiments in the move to SLC5 Extensively tested and production ready Confident on a quick and painless transition No known showstoppers for a large scale migration SL(C) 5 Migration at CERN - 14

CERN IT Department CH-1211 Genève 23 Switzerland t Questions? Thank you for listening! Questions? SL(C) 5 Migration at CERN - 15

CERN IT Department CH-1211 Genève 23 Switzerland t References SL(C) 5 Migration at CERN - 16

CERN IT Department CH-1211 Genève 23 Switzerland t Abstract SLC5 deployment at CERN Despite of the unfortunate delay of LHC data taking, the ramping up of available resources at CERN continues. New deliveries of CPU resources are expected for early In order to be able to make optimal use of the expected modern hardware, appropriate Linux hardware drivers must be provided. For the current main stream SLC4 it becomes increasingly difficult to get suitable backports and support for such drivers. The delay of the LHC data taking offers the opportunity to migrate to the more recent SL5 which should solve this problem. In autumn 2008, CERN has set up a couple of public interactive and batch worker nodes for evaluation by the experiments, and has set up a Grid preproduction pilot. The current plan foresees that the coming computing resources are made available under this new operating system. The status of the migration, feedback and challenges are described in the presentation. Beyond this, the migration to a new operating system also offers an excellent opportunity to upgrade the infrastructure used to manage the servers. Upgrades which directly affect users will be described. SL(C) 5 Migration at CERN - 17