Regarding changelog performance. I've seen up to 20% or more performance degradation (from optimal /w changelogs disabled) depending on how large your mask is. I suspect this is a result of the additional writes required to populate all of the records.
-cf On Thu, Jan 12, 2023 at 8:04 AM thomas.leibov...@cea.fr < thomas.leibov...@cea.fr> wrote: > Dear Rémi, > > Happy to see a new deployment of RobinHood in France in a sister company > of CEA :) > > Here are some answers to your questions: > > 1) I never measured precisely the impact of changelogs, but I'd say it is > not significant and not noticeable by users. AFAIR, I saw some > presentations talking about 5% of metadata performance degradation. > Perhaps Sebastien Buisson (in cc) who worked on using changelog for > security audit logs (which is more heavy than the default mask) can give us > this information. > > 2) Basically PFL makes Lustre use a different striping as a file grow > (e.g. stripe_count=1 for the first 10MB, then stripe_count=2 up to 1GB > etc..), so the beginning of the file may be located on different OSTs than > the rest of the file. > More info here: https://wiki.lustre.org/Configuring_Lustre_File_Striping > > rbh3 is aware of PFL, but only considers the current striping of the file > (not the first blocks). > A consequence is that the command like "rbh-find -ost xxx" may not report > the small blocks at the beginning of the file but only the current file > striping based on the current file size. > > 3) rbh4 is available here: > https://github.com/robinhood-suite > > For now it can only been used in scan mode, but the Lustre changelog > reader is close to be completed. We would be very happy if you beta test it! > My colleagues in cc will be happy to give you more information in needed. > We can schedule a call soon (in French) to discuss about it. > > Best Regards, > Thomas > ________________________________________ > De : Rémi Palancher <r...@rackslab.io> > Envoyé : jeudi 12 janvier 2023 10:24 > À : robinhood-support@lists.sourceforge.net > Objet : [robinhood-support] Feedback on RobinHood > > Hi RobinHood developpers and users, > > I am studying with EDF the opportunity to deploy RobinHood on their HPC > clusters running Lustre 2.12. > > We are particularly interested on any feedback about: > > - The impact on filesystem performances of the activation of Lustre > changelog with default event mask [0]? Does anyone has numbers to share? > > - The current state of Lustre PFL support? The last "RobinHood Project > Update" slides available in the wiki from 2017 [1] say « no PFL support for > now » but commit in 2019 mentions a « workaround to support PFL » [2]. I > must admit I am not an experienced Lustre expert and I don't fully > understand the comment « It only stores and handles the striping > information of the last > initialized component of a layout, which is likely the one suited for the > current file size. » What are the caveats and the limits of the current > workaround? > > - The roadmap for v4? I saw these slides from LAD'22 that mentions tests > in 2023. Do you plan any release this year? > > Thank you in advance for any kind of answer! > > Best regards, > > [0] > https://github.com/cea-hpc/robinhood/blob/master/scripts/rbh-config#L298 > [1] > https://robinhood.sourceforge.net/rug17/RUG17-ThomasLeibovici-ProjectUpdate.pdf > [2] > https://github.com/cea-hpc/robinhood/commit/7ba46d66970d476d25e3890848592c0c5979b666 > [3] > https://www.eofs.eu/_media/events/lad22/1.7-rbh4_update_sebastiengougeaud.pdf > > -- > Rémi Palancher > Rackslab: Open Source Solutions for HPC Operations > https://rackslab.io > > > _______________________________________________ > robinhood-support mailing list > robinhood-support@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/robinhood-support > > > _______________________________________________ > robinhood-support mailing list > robinhood-support@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/robinhood-support >
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