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List:       lustre-discuss
Subject:    Re: [lustre-discuss] inotify
From:       Andreas Dilger <adilger () whamcloud ! com>
Date:       2019-05-06 19:50:38
Message-ID: B1C040E7-EA5B-46BF-A6DF-3C0F084BC344 () whamcloud ! com
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On Apr 23, 2019, at 11:16, Faaland, Olaf P. <faaland1@llnl.gov> wrote:
> 
> Hi,
> 
> > Does inotify work on Lustre and if so, are there any caveats (performance, \
> > functionality, or otherwise)? 

AFAIK, inotify does *not* work correctly on Lustre, because it is purely a
local VFS mechanism.  That means it _might_ work for a small number of files
that are accessed/cached locally on the client, but definitely the client
would not be notified of changes that are happening on other clients.

Hooking inotify into the Lustre Changelog mechanism might be possible, so
that _select_ clients which need full inotify functionality could be added
as changelog consumers, and Changelog records would be mapped to inotify
events, but I think there would be a very significant overhead if a large
number of clients were all trying to be notified of every even in the whole
filesystem...

Cheers, Andreas
--
Andreas Dilger
Principal Lustre Architect
Whamcloud

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