[lustre-discuss] Full OST, any way of avoiding it without hanging?

Jason Williams jasonw at jhu.edu
Mon Jan 7 11:09:33 PST 2019

Thank you again Rick.

One last question, How safe is lfs_migrate?  The man page on the installation says it's UNSAFE for possibly in-use files.  The lustre manual doesn't have the same warning and says something about it being a bit more integrated with the MDS.


How safe do you think this would be to run on some files on the OST with it disabled on the MDS and active jobs running on the cluster?  I could do this by group, possibly to mitigate concerns of open files, if need be.

Jason Williams
Assistant Director
Systems and Data Center Operations.
Maryland Advanced Research Computing Center (MARCC)
Johns Hopkins University
jasonw at jhu.edu<mailto:jasonw at jhu.edu>

From: Mohr Jr, Richard Frank (Rick Mohr) <rmohr at utk.edu>
Sent: Monday, January 7, 2019 1:07 PM
To: Jason Williams
Cc: lustre-discuss at lists.lustre.org
Subject: Re: [lustre-discuss] Full OST, any way of avoiding it without hanging?

> On Jan 7, 2019, at 12:53 PM, Jason Williams <jasonw at jhu.edu> wrote:
> As I have gone through the testing, I think you may be right.  I think I disabled the OST in a slightly different way and that caused issues.
> Do you happen to know where I could find out a bit more about what the "lctl set_param osp.<osc_name>.max_create_count=0” command would do?

The Lustre manual has a section on removing MDTs/OSTs:


Rick Mohr
Senior HPC System Administrator
National Institute for Computational Sciences

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