[Lustre-discuss] [Lustre-community] Create directory where files get striped over the same set of OSTs

[Kshitij Mehta]

We have Lustre v 1.6.7, so I don't think we have OST pools. 
We have an application that generates a few files. We wanted to test the
performance over a subset of OSTs. However, we end up hitting all OSTs,
since the different files get created over a different set of OSTs.  

Thanks for your reply,

Kshitij Mehta
PhD Candidate
Parallel Software Technologies Lab (pstl.cs.uh.edu)
Dept. of Computer Science
University of Houston
Houston, Texas, USA


-----Original Message-----
From: Wynkoop, John Louis [mailto:jwynkoop at utk.edu] 
Sent: Thursday, February 09, 2012 7:39 PM
To: Kshitij Mehta
Subject: Re: [Lustre-community] Create directory where files get striped
over the same set of OSTs

Kshitij,

You can consider using stripe offsets (IE: lfs setstripe -i 0), this will
configure Lustre to start the striping on the same OST each time.   To
keep the files confined to a certain set of OSTs, you should look into OST
pools.  You didn't mention your version of Lustre, but anything 1.8 or later
should have support for pools.  Just out of curiosity, why do you want to
limit which OSTs you are using?  That will greatly affect the usage balance
across your OSTs and reduce your total throughput.  Hope this helps.

--
John Wynkoop
HPC System Administrator
National Institute for Computational Sciences The University of Tennessee,
Knoxville
email: jwynkoop at utk.edu




On 2/9/12 6:24 PM, "Kshitij Mehta" <kmehta at cs.uh.edu> wrote:

>Hello,
>My lustre installation has a total of 64 OSTs and I have created a
>directory that has been configured over 8 OSTs.
>However, files in this directory get striped over different OSTs. For
>example,
>file 1 might get striped over OSTs 0 thru 7, whereas file 2 might get
>striped over OSTs 8 thru 15.
>
>How can I configure a directory so that files in it get striped across
>the *same* set of OSTs?
>
>Thanks,
>Kshitij Mehta
>PhD candidate
>Parallel Software Technologies Lab (pstl.cs.uh.edu)
>Dept. of Computer Science
>University of Houston
>Houston, Texas, USA
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