---------------------------------------------------------------------- H H PPP CCC UK NATIONAL HPC SERVICE H H P P C C -------------------------- HHHHH PPP C x x provided by H H P C C xx EPCC and H H P CCC x x CCLRC Daresbury Laboratory ---------------------------------------------------------------------- HPCx User Mailing 060 4 February 2005 ---------------------------------------------------------------------- Contents ** Course: Message-Passing Programming with MPI ** Tape store: reclaiming space ---------------------------------------------------------------------- Greetings-- COURSE: MESSAGE-PASSING PROGRAMMING WITH MPI Tuesday-Thursday, 22-24 February 2005, at EPCC, Edinburgh The world's largest supercomputers are used almost exclusively to run applications which are parallelised using Message Passing. The course covers all the basic knowledge required to write parallel programs using this programming model, and is directly applicable to almost every parallel computer architecture. There will be opportunities to discuss your particular applications with HPCx staff members. The course uses the de facto standard for message passing, the Message Passing Interface (MPI). Course description: http://www.epcc.ed.ac.uk/computing/training/courses/course_summaries/MessagePass ing_summary.html Registration form: http://www.hpcx.ac.uk/support/training/form.html This course is usually oversubscribed. Register now - it's first come, first served. ---------------------------------------------------------------------- TAPE STORE: RECLAIMING SPACE This important note is for users of the tape store. Tape is a sequential medium. You can only write files at the current end of a tape, after all the other files. You can delete a file, but if you do, the hole can't be reused. To get round this problem, there is a process on the system which reclaims this space for use, by shuffling the files down to fill up the holes. It starts to do this automatically, once the the holes amount to more than a particular threshold, which we have set to 10% of the space. But to do this, it needs an empty scratch tape to park your files as it works. And the empty tape must belong to your project. If there is no empty tape, the reclamation stalls. (For this reason, we never allocate only a single tape - you must have at least two.) So this means you shouldn't wait until all your tapes are in use before deleting some files. Start deleting while there is still at least one tape completely free. ---------------------------------------------------------------------- Regards --John ---------------------------------------------------------------------- Earlier mailings: http://www.hpcx.ac.uk/support/notices/index.html To be removed from the mailing list: log into your website account, go to the "Update" page, and click the "Opt out of user emails" field; then click "Commit update". -- John Fisher j.fisher@epcc.ed.ac.uk HPCx User Administration and Helpdesk HPCx: http://www.hpcx.ac.uk Helpdesk: support@hpcx.ac.uk Phone: +44 131 650 5029 Fax: +44 131 650 6555