[Lustre-discuss] strange symbolic link behavior on mdt?

Dilger, Andreas andreas.dilger at intel.com
Mon Oct 13 13:37:49 PDT 2014

On 2014/10/13, 12:22 PM, "Kristen J. Webb" <kwebb at teradactyl.com> wrote:

>I am testing symbolic link behaviour
>and not getting the expected results.
>In the simplest case, I create one valid
>and one invalid link:
>-rw-r--r-- 1 root root 0 Oct 13 11:17 exist
>lrwxrwxrwx 1 root root 5 Oct 13 11:17 lexist -> exist
>lrwxrwxrwx 1 root root 7 Oct 13 11:17 lnoexist -> noexist
>When I look at the meta data through the ldiskfs mounted mdt
>the link paths are not shown:
>-rw-r--r-- 1 root root 0 Oct 13 11:17 exist
>lrwxrwxrwx 1 root root 5 Oct 13 11:17 lexist
>lrwxrwxrwx 1 root root 7 Oct 13 11:17 lnoexist

You shouldn't be mounting the MDT directly as ldiskfs while it is already
mounted as Lustre.  There is no attempt made to maintain cache coherency
between the Lustre and ldiskfs mount points.

Presumably the symbolic links worked fine on another Luster client?

Cheers, Andreas

>And trying to get a bit more info:
># file *
>exist:    empty
>lexist:   unreadable symlink `lexist' (Invalid argument)
>lnoexist: unreadable symlink `lnoexist' (Invalid argument)
>If I restart lustre by unmounting and re-mounting
>all the lustre mount points (MDT, ODT's, client)
>the link paths show up in the ldiskfs mounted mdt:
>-rw-r--r-- 1 root root 0 Oct 13 11:17 exist
>lrwxrwxrwx 1 root root 5 Oct 13 11:17 lexist -> exist
>lrwxrwxrwx 1 root root 7 Oct 13 11:17 lnoexist -> noexist
>file *
>exist:    empty
>lexist:   symbolic link to `exist'
>lnoexist: broken symbolic link to `noexist'
>I've also just tried just re-mounting the ldiskfs mount
>point but that did not help.
>Is there any way to correct this without having to restart lustre?
>I experimented with running lfsck w/o restart all of lustre
>but I could not see that it was running or had done anything
>useful yet.
>This message is NOT encrypted
>Mr. Kristen J. Webb
>Chief Technology Officer
>Teradactyl LLC.
>2450 Baylor Dr. S.E.
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>Phone: 1-505-338-6000
>Email: kwebb at teradactyl.com
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Cheers, Andreas
Andreas Dilger

Lustre Software Architect
Intel High Performance Data Division

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