[FLASH-USERS] Changing Stripe size

[Rukmani Vijayaraghavan]

Hi Kevin,

I recently ran into this exact issue on Stampede, when running on ~7000 -
8000 cores. I contacted the Stampede admins, and this is how they suggested
I fix the problem -- this fix works. I'm copying their response here:

""
In order to set the stripe count to 40 (note: default is 2 on $SCRATCH), I
mostly switch to the parent directory of the directory I want to write the
data in and run the "lfs setstripe..." command. So for example, if I want
to write a large file in a directory named "TACC" at the path
"/scratch/01698/user/ticket", I will switch to "/scratch/01698/user/ticket"
and run the command below:

login4$ lfs setstripe -c 40 TACC

The above command will set the stripe count of 40 on the directory named
"TACC". You can test whether the stripe count got set correctly or not by
creating a test file and checking its stripe count using the "lfs
getstripe..." command.

login4$ cd TACC
login4$ vi test.del
login4$ lfs getstripe test.del

 Upon running the above command, you will see some information as below:
test.del lmm_stripe_count: 40 lmm_stripe_size: 1048576 lmm_layout_gen: 0
lmm_stripe_offset: 54 ... The setting for stripe-count will be maintained
till someone explicitly resets it. Also note that when you move the files
in a directory (using the "mv" command), the stripe count set at the source
location is honored at the destination location. However, if you will copy
a file to a directory (using the "cp" command), the stripe count set at the
destination directory will be honored.
""

Additionally, I suggest using phdf5 on stampede if you aren't already, IO
speeds are vastly improved.

Best,
Rukmani
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://flash.rochester.edu/pipermail/flash-users/attachments/20140816/9ad0fcac/attachment.htm>