CSAR Bulletin issued in September 2002

SAN: Installation Complete

The installation of the SAN is now complete and all users home directories have been moved from disk directly attached to Fermat, to the SAN. You can therefore now access your home directory directly from Fermat, Green and Wren. PIs can trade now for High Performance disk and High Volume disk. However we ask that all PIs who wish to use any of the new disks contact CSAR to discuss their requirements, and also complete the capacity plans, so that CSAR has a clear indication of the demand for each disk type.

All existing users of Fermat will have a new account on Wren, which will shortly be the only Origin system providing an interactive service.

The next phase in this process will be to remove interactive access to Fermat. We therefore urge all Fermat users to start using Wren as soon as possible and to report any problems. You should note that there are some differences in the way Wren and Fermat are used, particularly with respect to applications software which as far as possible is now held in a single location on the SAN (the directory /share/apps/), rather than in local directories on each machine (/usr/local/). The use of the module command to access much of this software is now recommended instead of explicit changes to your paths.

Further details on the SAN resources are available in link to SAN pages

Please note that the date for removal of interactive access to Fermat is expected to be mid to late October, and will be after the date when the NQE service is replaced by LSF (see below). Further notice on the exact date will be given at least one week prior to the removal from service. We therefore encourage all users to start using Wren for all interactive work as soon as possible.

LSF: Please Test

The primary motivation for moving from NQE to LSF is the ability to use dynamic cpusets. This feature provides the best possible way of isolating jobs and minimising interference between them, particularly with respect to shared memory. The major benefit to users is in minimising variability in job times. Testing with LSF and production runs using a 128 processor cpuset have given excellent results - showing variation of less than 1%.

We are in the final stages of testing LSF - you may be aware that some processors on Wren, Fermat and Green are currently reserved for LSF and therefore inaccessible to normal batch jobs run via NQE. Valuable feedback has been received from some users who have already been testing LSF and we will shortly be replacing NQE by LSF on all three Origin systems. This will mean that all users must modify job submission scripts to use LSF instead of NQE. From the feedback so far, it is believed this is a very simple task, and a basic conversion script is available to help in this transition. LSF is installed on all three Origin systems and you can submit (small) jobs to any of the machines to test your scripts. We therefore encourage you to test LSF versions of your job submission scripts as soon as possible, so that your jobs can be run immediately when the conversion takes place. Please report any problems encountered in using LSF.

Further details about using LSF are available in LSF User Guide

Please note that the date for replacement of NQE by LSF is expected to be early to mid-October (Tuesday 8th October is the earliest possibility). Further notice on the exact date will be given at least one week prior to the change.