Hi Ceph Users, My goal is to control the number of files a ceph client can open to the backend ceph filesystem at once to control the metadata transaction load. In this experiment, I have a ceph client on version Quincy on a physical server. The fstab entry below shows the options with which the ceph filesystem is mounted on it. In particular, I used caps_max=1900 option with the intention to limit the total number of open files by this client at once to 1900 at the mount point /ourdisk/hpc_scratch. # cat /etc/fstab ... 10.251.0.30:6789,10.251.0.31:6789,10.251.0.32:6789,10.251.0.33:6789,10.251.0.40:6789:/volumes/hpc_scratch/scratch/525205e7-4f71-4383-89ce-53e2ec68d017 /ourdisk/hpc_scratch ceph fsc,caps_max=1900,name=oscer,secretfile=/etc/ceph/client.oscer.secret 0 0 To test if this worked, I used fio command to create 4000 files at once in a directory on Ceph at /ourdisk/hpc_scratch/soumya/fio_tests/client_c003. During the run, I looked at the caps file (copied below), and it shows the number of used caps is 4007. Given my limited knowledge, it seems to me that the client was able to open 4000 files at once. # head /sys/kernel/debug/ceph/d5d5b0aa-1867-11eb-9f4a-bc97e1724ff1.client483151133/caps total       5032 avail       1025 used        4007 reserved    0 min         1024 ino mds issued implemented -------------------------------------------------- 0x200136e01b6 0 pAsLsXsFs pAsLsXsFs 0x1 0 pAsLsXsFs pAsLsXsFs Is there any way I can control how many simultaneous files a ceph client can open (preferably from the client side, if not then from the ceph side but on an individual client)? If so, how can I check the number of files a client is opening at a given time? Thank you for your time, Soumya PS: I understand that the number of capabilities is not the number of open files, but that's the closest mount option I could find for this experiment.