I've seen your other thread. Using 78GB of RAM when the memory limit is set to 64GB is not highly unusual, and doesn't necessarily indicate any problem. It *would* be a problem if the MDS memory grows uncontrollably, however. Otherwise, check those new defaults for caps recall -- they were released around 14.2.19 IIRC. -- Dan On Wed, May 26, 2021 at 12:46 PM Andres Rojas Guerrero <a.rojas@xxxxxxx> wrote: > > Thanks for the answer. Yes, during these last weeks I have had memory > consumption problems in the MDS nodes that led, at least it seemed to > me, to performance problems in CephFS. I have been varying, for example: > > mds_cache_memory_limit > mds_min_caps_per_client > mds_health_cache_threshold > mds_max_caps_per_client > mds_cache_reservation > > But without much knowledge and with a trial and error procedure, i.e. > observing how CephFS behaved when changing one of the parameters. > Although I have achieved improvement the procedure does not convince me > at all and that's why I was asking if there was something more reliable ... > > > > > El 26/5/21 a las 12:15, Dan van der Ster escribió: > > Hi, > > > > The mds_cache_memory_limit should be set to something relative to the > > RAM size of the MDS -- maybe 50% is a good rule of thumb, because > > there are a few cases where the RSS can exceed this limit. Your > > experience will help guide what size you need (metadata pool IO > > activity will be really high if the MDS cache is too small) > > > > Otherwise, in recent releases of N/O/P the defaults for those settings > > you mentioned are quite good [1]; I would be surprised if they need > > further tuning for 99% of users. > > Is there any reason you want to start adjusting these params? > > > > Best Regards, > > > > Dan > > > > [1] https://github.com/ceph/ceph/pull/38574 > > > > On Wed, May 26, 2021 at 11:58 AM Andres Rojas Guerrero <a.rojas@xxxxxxx> wrote: > >> > >> Hi all, I have observed that the MDS Cache Configuration has 18 parameters: > >> > >> mds_cache_memory_limit > >> mds_cache_reservation > >> mds_health_cache_threshold > >> mds_cache_trim_threshold > >> mds_cache_trim_decay_rate > >> mds_recall_max_caps > >> mds_recall_max_decay_threshold > >> mds_recall_max_decay_rate > >> mds_recall_global_max_decay_threshold > >> mds_recall_warning_threshold > >> mds_recall_warning_decay_rate > >> mds_session_cap_acquisition_throttle > >> mds_session_cap_acquisition_decay_rate > >> mds_session_max_caps_throttle_ratio > >> mds_cap_acquisition_throttle_retry_request_timeout > >> mds_session_cache_liveness_magnitude > >> mds_session_cache_liveness_decay_rate > >> mds_max_caps_per_client > >> > >> > >> > >> I find the Ceph documentation in this section a bit cryptic and I have > >> tried to find some resources that talk about how to tune these > >> parameters, but without success. > >> > >> Does anyone have experience in adjusting these parameters according to > >> the characteristics of the Ceph cluster itself, the hardware and the use > >> of MDS? > >> > >> Regards! > >> -- > >> ******************************************************* > >> Andrés Rojas Guerrero > >> Unidad Sistemas Linux > >> Area Arquitectura Tecnológica > >> Secretaría General Adjunta de Informática > >> Consejo Superior de Investigaciones Científicas (CSIC) > >> Pinar 19 > >> 28006 - Madrid > >> Tel: +34 915680059 -- Ext. 990059 > >> email: a.rojas@xxxxxxx > >> ID comunicate.csic.es: @50852720l:matrix.csic.es > >> ******************************************************* > >> _______________________________________________ > >> ceph-users mailing list -- ceph-users@xxxxxxx > >> To unsubscribe send an email to ceph-users-leave@xxxxxxx > > -- > ******************************************************* > Andrés Rojas Guerrero > Unidad Sistemas Linux > Area Arquitectura Tecnológica > Secretaría General Adjunta de Informática > Consejo Superior de Investigaciones Científicas (CSIC) > Pinar 19 > 28006 - Madrid > Tel: +34 915680059 -- Ext. 990059 > email: a.rojas@xxxxxxx > ID comunicate.csic.es: @50852720l:matrix.csic.es > ******************************************************* _______________________________________________ ceph-users mailing list -- ceph-users@xxxxxxx To unsubscribe send an email to ceph-users-leave@xxxxxxx
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