[Lustre-discuss] Enable async journals

[Frank Heckes]

Hi Ihara,

> Frank,
> 
> > tune2fs -O ^has_journal<ost-device>  on all OSSes for all all OSTs
> 
> What is a reason of removing the journal feature? You should have the journal even whether you want to enable
> async_journal or not.
>
That was actually the question. Many thanks for the clarification.

> Also, as far as I could see, in general, without enabling async journal, we could see better performance on using
> external journals rather than the internal journal.
> However, once async_journal is enabled, we could see same (in some case, better) performance even the
> internal journal is used.
> 
Well, the reason why this feature is so interessting is described in
paper:

http://www.usenix.org/events/fast10/tech/full_papers/oral.pdf

It confirms your first statement. Anyway async journal feature seems to
improve any 'low-level' HW solution. 
Many thanks for the comments.

-Frank 

> Thanks
> Ihara
> 
> (7/13/10 9:53 PM), Frank Heckes wrote:
> > Hi all,
> >
> > we use SLES 11 and Lustre 1.8.1.1 + patches and like convert a lustre FS
> > using external journals to one with async journals enabled.
> > Question is whether the procedure:
> >
> > umount<filesystem>              on all clients
> > umount<osts>                    on all OSSes
> > e2fsck<ost-device>              on all OSSes for all all OSTs
> > tune2fs -O ^has_journal<ost-device>  on all OSSes for all all OSTs
> > lctl set_param obdfilter.*.sync_journal=0  on all OSSes
> > mount<osts>                     on all OSSes
> > mount<filesystem>               on all clients
> >
> > is correct to do the job? (I hope it isn't neccessary to recreate a FS
> > from scratch.) Many thanks in advance.
> >
> > Cheers
> >
> > -Frank Heckes
> >
> > P.S.: 1.8.1.1 still contains some bugs which have been fixed in 1.8.3.
> > Described setup is for test purpose only, but the procedure shall be
> > used in the final environment (using lustre 1.8.3), too.
> >
> >
> >
> > ------------------------------------------------------------------------------------------------
> > ------------------------------------------------------------------------------------------------
> > Forschungszentrum Juelich GmbH
> > 52425 Juelich
> > Sitz der Gesellschaft: Juelich
> > Eingetragen im Handelsregister des Amtsgerichts Dueren Nr. HR B 3498
> > Vorsitzender des Aufsichtsrats: MinDirig Dr. Karl Eugen Huthmacher
> > Geschaeftsfuehrung: Prof. Dr. Achim Bachem (Vorsitzender),
> > Dr. Ulrich Krafft (stellv. Vorsitzender), Prof. Dr.-Ing. Harald Bolt,
> > Prof. Dr. Sebastian M. Schmidt
> > ------------------------------------------------------------------------------------------------
> > ------------------------------------------------------------------------------------------------
> > _______________________________________________
> > Lustre-discuss mailing list
> > Lustre-discuss at lists.lustre.org
> > http://lists.lustre.org/mailman/listinfo/lustre-discuss
> _______________________________________________
> Lustre-discuss mailing list
> Lustre-discuss at lists.lustre.org
> http://lists.lustre.org/mailman/listinfo/lustre-discuss