[lustre-discuss] Lustre chown and create operations failing for certain UIDs

[Harr, Cameron]

Russell,

Your symptoms are a little different from what I see when the MDS node's 
passwd file is incomplete, but did you verify the affected_user has a 
proper /etc/passwd entry on the MDS node(s)?

On 1/10/19 12:14 PM, Russell Dekema wrote:
> We've got a Lustre system running lustre-2.5.42.28.ddn8 and are having
> a problem with it that none of us here have ever seen before. We are
> wondering if anyone here has seen this or has any idea what might be
> causing it.
>
> (I have redacted the example affected username and its corresponding
> UID in this message for privacy reasons, and replaced them with the
> strings 'affected_username' and 'uid_of_the_affected_username'.)
>
> Of the 4,463 UIDs on our system, there are 24 UIDs for which Lustre
> returns an error when those UIDs are used as the owner of files in a
> chown or create operation, as in:
>
> # chown affected_username testfile
> chown: changing ownership of ‘testfile’: No such process
>
> This occurs both when root tries to chown a file for the affected UID
> and when the user corresponding to that UID tries to create a file in
> a directory to which they otherwise have the proper permissions.
>
> If, as root, we run "strace chown affected_username testfile", the
> system call that fails appears to be:
>
> fchownat(AT_FDCWD, "testfile", uid_of_the_affected_username, -1, 0) =
> -1 ESRCH (No such process)
>
> Another unusual thing we have noticed about these users is that we are
> unable to look up their quotas on the Lustre filesystem, even though
> quota lookups work fine for other users:
>
> $ sudo lfs quota -u affected_username /scratch
> usr quotas are not enabled.
>
> If anyone has any ideas about what might be causing this or what we
> might try in order to fix or further diagnose it, I'll be glad to hear
> them. We do have a ticket open with our vendor but wanted to see if
> anyone else had heard of this while we await their response.
>
> Sincerely,
> Rusty Dekema
> University of Michigan
> Advanced Research Computing - Technology Services
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