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 _______________________________________________ ceph-users mailing list -- ceph-users@xxxxxxx To unsubscribe send an email to ceph-users-leave@xxxxxxx
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