[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.


http://doc.lustre.org/lustre_manual.xhtml#dbdoclet.lfs_migrate


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:

http://doc.lustre.org/lustre_manual.xhtml#dbdoclet.deactivating_mdt_ost

--
Rick Mohr
Senior HPC System Administrator
National Institute for Computational Sciences
http://www.nics.tennessee.edu


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