[Lustre-discuss] Log file opens/reads/etc?

[Andreas Dilger]

On Aug 20, 2008  13:58 -0700, daledude wrote:
> On Aug 18, 6:43 am, Andreas Dilger <adil... at sun.com> wrote:
> > On Aug 09, 2008  05:06 -0700, daledude wrote:
> >
> > > Is there is a tool that shows what files are being accessed? Sort of
> > > like inotify, but not inotify? I'd like to compile file access
> > > statistics to try and balance the most accessed files across the OST's
> > > better.
> >
> > There is a feature being worked on for Lustre 2.0 called "Changelogs"
> > that will allow recording all files that are modified.
> 
> Is there a "debug" tool/option/log in 1.6.5 that outputs what files
> are being opened or read? Im more interested in reads. Im not using
> striping so I'd like to find out what files are accessed the most so
> they can be copied to less overloaded OST's.

Not really.  You could add a CDEBUG message in the read code
(ost_brw_read() that prints the object number) so it is logged to the
lustre debug log, and then run "lctl debug_daemon" to continuously
log these messages to disk.  This would of course have some performance
impact.

Cheers, Andreas
--
Andreas Dilger
Sr. Staff Engineer, Lustre Group
Sun Microsystems of Canada, Inc.