[lustre-discuss] MGTMDT device getting full

Dilger, Andreas andreas.dilger at intel.com
Fri Oct 16 15:09:21 PDT 2015

On 2015/10/16, 12:03, "lustre-discuss on behalf of Torsten Harenberg"
<lustre-discuss-bounces at lists.lustre.org on behalf of
torsten.harenberg at cern.ch> wrote:

>Thanks Chris for both of your mails.
>One of my users is already heavily deleting files. Of course metadata
>usage goes down now, but too early to conclude if that will recover a
>substancial amount of space.

If MDT usage is going down when files are deleted, it is likely due to
file striping.  Do you perhaps have a default stripe count >= 7 for all
files?  That would consume an additional 4KB per file on the MDT, in
addition to slowing down file access.

Better to reduce the default stripe count and only set a high stripe count
for files (or defaults on their parent directories) that are going to be

Cheers, Andreas

>Am 16.10.2015 um 19:50 schrieb Christopher J. Morrone:
>> Oh.  Doh.  I missed the low Inode usage that you listed in your first
>> email.   Ben was right, that kind of does point to some runaway log
>> files like changelogs.  Perhaps you enabled them by accident?  Do you
>> have any kind of HSM?  It would be good to check the changelog_users
>> regardless.
>I cannot remember doing it - only started reading about that feature
>after Ben's mail. And I think the results before (see my mail which
>"crossed" yours)  show that this is not activated.
>Other stuff I checked
>[root at lustre2 ~]# lctl get_param debug
>debug=ioctl neterror warning error emerg ha config console
>There is no  HSM, also no HA. But the data is on a SAN backend and a 2nd
>server is running on "hot standby". After bad experience with HA with an
>old Lustre cluster in the past, I left it that way.
>> If that doesn't show anything, you probably need to mount your MDT's
>> backend filesystem as a local filesytem (readonly) and look for where
>> the space is going.
>Let me guess: that cannot be done while Lustre is active, or?
>Thanks again
>  Torsten
><>                                                              <>
><> Dr. Torsten Harenberg     Torsten.Harenberg at cern.ch          <>
><> Bergische Universitaet                                       <>
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><> Gaussstr. 20              Fax : +49 (0)202 439-2811          <>
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Cheers, Andreas
Andreas Dilger

Lustre Software Architect
Intel High Performance Data Division

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