We have a 23 node cluster and normally when we add OSDs they end up mounting like this:
/dev/sde1 3.7T 2.0T 1.8T 54% /var/lib/ceph/osd/ceph-15
/dev/sdj1 3.7T 2.0T 1.7T 55% /var/lib/ceph/osd/ceph-20
/dev/sdd1 3.7T 2.1T 1.6T 58% /var/lib/ceph/osd/ceph-14
/dev/sdc1 3.7T 1.8T 1.9T 49% /var/lib/ceph/osd/ceph-13
I'm pretty sure those OSDs have been deployed with Filestore backend as the first partition of the device is the data partition and needs to be mounted.
However I noticed this morning that the 3 new servers have the OSDs mounted like this:
tmpfs 47G 28K 47G 1% /var/lib/ceph/osd/ceph-246
tmpfs 47G 28K 47G 1% /var/lib/ceph/osd/ceph-240
tmpfs 47G 28K 47G 1% /var/lib/ceph/osd/ceph-248
tmpfs 47G 28K 47G 1% /var/lib/ceph/osd/ceph-237
And here, it looks like those OSDs are using Bluestore backend because this backend doesn't need to mount any data partitions. What you're seeing is the Bluestore metadata in this tmpfs. You should find in the mount point some usefull information (fsid, keyring and symlinks to the data block and/or db/wal). I don't know if you're using ceph-disk or ceph-volume but you can find information about this by running either: - ceph-disk list - ceph-volume lvm list