[ceph-users] Pacific - MDS behind on trimming

Hi, lately, we have had some issues with our MDSs (Ceph version 16.2.10 Pacific). Part of them are related to MDS being behind on trimming. I checked the documentation and found the following information ( https://docs.ceph.com/en/pacific/cephfs/health-messages/): The length of journal (in number of segments) is controlled by the setting mds_log_max_segments, and when the number of segments exceeds that setting the MDS starts writing back metadata so that it can remove (trim) the oldest segments. If this writeback is happening too slowly, or a software bug is preventing trimming, then this health message may appear. The threshold for this message to appear is controlled by the config option mds_log_warn_factor, the default is 2.0. Some resources on the web (https://www.suse.com/support/kb/doc/?id=000019740) indicated that a solution would be to change the `mds_log_max_segments`. Which I did: ``` ceph --cluster floki tell mds.* injectargs '--mds_log_max_segments=400000' ``` Of course, the warning disappeared, but I have a feeling that I just hid the problem. Pushing a value to 400'000 when the default value is 512 is a lot. Why is the trimming not taking place? How can I troubleshoot this further? Best, Emmanuel