------ Forwarded Message
From: Michael Ernst <[log in to unmask]>
Date: Thu, 05 Mar 2009 18:09:30 -0500
To: Rob Gardner <[log in to unmask]>, "McKee, Shawn" <[log in to unmask]>,
Saul Youssef <[log in to unmask]>, Wei Yang <[log in to unmask]>
Subject: FW: re-processing campaign has started

All,
 this is to let you know that the reprocessing exercise has started. This
morning validation jobs were submitted to the US cloud and finished
successfully at AGLT2.

Please find more information from Kors below.

--
    Michael
------ Forwarded Message
From: Kors Bos <[log in to unmask]>
Date: Thu, 5 Mar 2009 17:47:31 -0500
To: <[log in to unmask]>
Conversation: re-processing campaign has started
Subject: re-processing campaign has started

All,

the validation tasks for the re-processing have been submitted or are
about to be submitted. These are very much like the tasks that were
run during the Christmas re-processing campaign. Last time these tests
revealed a problem in FZK but that is now understood and fixed. So we
don't expect any site to fail this time. However Taipei is down
because of the fire and won't be back up in time to participate. These
data have to be re-processed at CERN now.

Tests have been performed at PIC and RAL to re-process data from tape.
This still uses the old release of the reconstruction software but
that is not important for this test. At PIC this went very well except
that the task didn't finish because we seem to have a broken tape. It
is good that this happens now because it gives us the opportunity to
test how to fix this. We can be sure that this will happen again. Also
at RAL this test is going well although a bit slower (on purpose).

All cosmics data has been cleaned from the buffers so the same tests
can start in the other T1's. Lyon will bring the files on-line
manually because there is still one component missing to have pre-
staging been done by the site services. These tests tell us if pre-
staging works and if the buffer turn over is more or less optimal for
the jobs.

The plan still is to start the real re-processing of all the cosmics
data next week. We know that there is a few day shut down at FZK so
they will probably start a little bit later. We don't have to remove
the RAW data from the disks because Panda can now distinguish between
the copy on disk and the copy on tape and be made to choose the tape
copy. This gives us a fall-back in case we do have problems with
reading from tape. We should hope not to need this fall back solution
because with real data we won't have an extra copy on disk.

We will have 2 measures against the "hot file" problem. There will be
a conditions data tar ball per run and not one for all 100 runs
together as we had over Christmas. So there will be fewer jobs at the
same time trying to access these data. Secondly at a few sites we will
test the "pcache solution" where the conditions data will be left on
the worker node after the job has finished. If the next job on that
node needs the same data it will just use it and not bring a fresh
copy in.

During Christmas and New Year few people were available in the sites.
This time we hope you will monitor closely this effort and report any
irregularity to us. We need to measure how efficiently we can do re-
processing, how many cpu's we use and how long it takes. We need to
know if the stage buffer matches the number of tape drives to fill it
and the number of cpu's to use it.  And then there are the exceptions
like broken tapes, files that seem to be missing for other reasons,
job crashes and so on. This may be one of the last chances to test
before we need it all working for real.

Kors


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