Hi, I'm currently doing cephfs backup, through a dedicated clients mounting the whole filesystem at root. others clients are mounting part of the filesystem. (kernel cephfs clients)
I have around 22millions inodes, before backup, I have around 5M caps loaded by clients #ceph daemonperf mds.x.x ---------------mds---------------- --mds_cache--- ---mds_log---- -mds_mem- --mds_server-- mds_ -----objecter------ purg req rlat fwd inos caps exi imi |stry recy recd|subm evts segs|ino dn |hcr hcs hsr |sess|actv rd wr rdwr|purg| 118 0 0 22M 5.3M 0 0 | 6 0 0 | 2 120k 130 | 22M 22M|118 0 0 |167 | 0 2 0 0 | 0 when backup is running, reading all the files, the caps are increasing to max (and even a little bit more) # ceph daemonperf mds.x.x ---------------mds---------------- --mds_cache--- ---mds_log---- -mds_mem- --mds_server-- mds_ -----objecter------ purg req rlat fwd inos caps exi imi |stry recy recd|subm evts segs|ino dn |hcr hcs hsr |sess|actv rd wr rdwr|purg| 155 0 0 20M 22M 0 0 | 6 0 0 | 2 120k 129 | 20M 20M|155 0 0 |167 | 0 0 0 0 | 0 then mds try recall caps to others clients, and I'm gettin some 2019-01-04 01:13:11.173768 cluster [WRN] Health check failed: 1 clients failing to respond to cache pressure (MDS_CLIENT_RECALL) 2019-01-04 02:00:00.000073 cluster [WRN] overall HEALTH_WARN 1 clients failing to respond to cache pressure 2019-01-04 03:00:00.000069 cluster [WRN] overall HEALTH_WARN 1 clients failing to respond to cache pressure Doing a simple echo 2 | tee /proc/sys/vm/drop_caches on backup server, is freeing caps again # ceph daemonperf x ---------------mds---------------- --mds_cache--- ---mds_log---- -mds_mem- --mds_server-- mds_ -----objecter------ purg req rlat fwd inos caps exi imi |stry recy recd|subm evts segs|ino dn |hcr hcs hsr |sess|actv rd wr rdwr|purg| 116 0 0 22M 4.8M 0 0 | 4 0 0 | 1 117k 131 | 22M 22M|116 1 0 |167 | 0 2 0 0 | 0 Some questions here : ceph side --------- Is it possible to setup some kind of priority between clients, to force retreive caps on a specific client ? Is is possible to limit the number of caps for a client ? client side ----------- I have tried to use vm.vfs_cache_pressure=40000, to reclam inodes entries more fast, but server have 128GB ram. Is it possible to limit the number of inodes in cache on linux. Is is possible to tune something on the ceph mount point ? Regards, Alexandre _______________________________________________ ceph-users mailing list ceph-users@lists.ceph.com http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
