Hi, From my LAD’17 presentation (https://www.eofs.eu/_media/events/lad17/13_sebastien_buisson_lustre_audit-1.1.pdf), we observed a 15% metadata performance drop for create and read, and 5% for remove. This is when enabling the full changelogs mask, and of course it might be different with a narrower mask. Note this is single client performance, which means the Lustre MDS server is not saturated at all. The performance penalty is incurred by the extra latency added by changelogs processing on server side though. Be also aware that these numbers are 5 years old.
Hope this helps, Sebastien. > Le 12 janv. 2023 à 15:17, thomas.leibov...@cea.fr a écrit : > > 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
