Hearns, John wrote:
I was wondering if somebody could help me here a bit.
For some of the calculations we are running on our cluster we need a
significant amount of disc space. The last calculation crashed as the ~700 GB
which I made available were not enough. So, I want to set up a RAID0 on one 8
core node with 2 1.5 TB discs. So far, so good.
Sounds like a cluster I might have had something to do with in a past life...
700 gbytes! My advice - look closely at your software and see why it needs this
scratch space,
and what you can do to cut down on this.
Heh... some of the coupled cluster GAMESS tests we have seen/run have
used this much or more in scratch space.
Single threaded readers/writers ... you either need a very fast IO
device, or like John suggested, you need to examine what is getting
read/written.
700GB @ 1GB/s takes 700 seconds, roughly 11m40s +/- some.
700GB @ 0.1GB/s takes 7000 seconds, roughly 116m40s +/- some (~2 hours).
A RAID0 stripe of two drives off the motherboard will be closer to the
second than the first ...
Also, let us know what code this is please.
You're right about network transfer of scratch files like that - if at all
possible,
you should aim to use local scratch space on the nodes.
$VENDOR (I think in Warwick!) should be very happy to help you there!
I know those guys! (and they are good).
--
Joseph Landman, Ph.D
Founder and CEO
Scalable Informatics Inc.
email: [email protected]
web : http://scalableinformatics.com
http://scalableinformatics.com/jackrabbit
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fax : +1 866 888 3112
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