Hi Roger, This sounds terribly familiar. The likely cause can be found by reading through the following thread:
http://lists.lustre.org/pipermail/lustre-discuss/2008-March/007024.html Note that running dumpe2fs on each device, as suggested by one of the messages in the thread, did *not* result in a performance improvement. j On May 30, 2008, at 1:25 PM, Roger Spellman wrote: > I am seeing the following odd behavior. I have several OSSes, each > with a 7T RAID 5. > > > > If I use a single client to create a single 1T file which is > striped to a single OST, the performance starts off at about 400 MB/ > s (which is typical for my HW), then gradually decreases, until it > reaches 250 MB/s. I’ve seen this with both IOZone and dd. > > > As an experiment, I wrote a script that creates two hundred 10G > files, without removing them. Again, the performance starts off at > 400 MB/s. But, the performance stays nearly the same throughout > the test. > > > > The only difference between these tests is that in the second case, > there are lots of opens & closes, and in the first case, just a > single open and close. > > > > Can anyone explain what is happening here, and how to possible fix it? > > > > Thanks. > > > > Roger Spellman > > Sr. Staff Engineer > > Terascala, Inc. > > > > _______________________________________________ > Lustre-discuss mailing list > [email protected] > http://lists.lustre.org/mailman/listinfo/lustre-discuss -- Jason Rappleye System Administrator NASA Advanced Supercomputing Division NASA Ames Research Center Moffett Field, CA 94035 [EMAIL PROTECTED] _______________________________________________ Lustre-discuss mailing list [email protected] http://lists.lustre.org/mailman/listinfo/lustre-discuss
