[lustre-discuss] Usage for lfs setstripe -o ost_indices

Ms. Megan Larko dobsonunit at gmail.com
Fri Nov 9 12:19:44 PST 2018

Responding to A. Dilger (orig e-mail copied below)
I am not sure what the overall objective is trying to achieve in
specifically identifying to which OSTs to write; it was a question from one
in our user community.   I am not able to specify -o to an existing file.
I have not tried to use the lustrelibapi to specify OST layout during the

I concur that LU-8417 points out a very significant disadvantage to having
users employ the -o option to "lfs setstripe" and that using Lustre Pools
is a better idea for the file system. (I'm speculating that perhaps the
users themselves want to be able to create such Lustre Pool-like areas and
currently only sysadmins may create Lustre Pools.  Avoid the
middle-man/woman!  Smile!)

Let me get back to my users to better understand what it is that needs to
be done causing them to wish to invoke the -o option to "lfs set-stripe".


A. Dilger wrote:
Andreas Dilger
12:51 PM (2 hours ago)

to Mohr, me, Lustre
This is https://jira.whamcloud.com/browse/LU-8417 "setstripe -o does not
work on directories", which has not been implemented yet.

That said, setting the default striping to specific OSTs on a directory is
usually not the right thing to do. That will result in OST imbalance.

Equivalent mechanisms include OST pools (which also allow a subset of OSTs
to be used, unlike -o currently does), and has the benefit of labeling
files with the pool to find them easier in the future (eg. for migrating
out of the pool).

What is the end goal that you are trying to achieve?

Cheers, Andreas
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