Understanding what ceph-volume does, with bootstrap-osd/ceph.keyring, tmpfs

Understanding what ceph-volume does, with bootstrap-osd/ceph.keyring, tmpfs

[Marc Roos]

When I create a new encrypted osd with ceph volume[1] 

I assume something like this is being done, please correct what is 
wrong.

- it creates the pv on the block device
- it creates the ceph vg on the block device
- it creates the osd lv in the vg
- it uses cryptsetup to encrypt this lv
  (or is there some internal support for luks in lvm?)
- it sets all the tags on the vg (shown by: lvs -o lv_tags vg)
- it creates and enables ceph-volume@lvm-osdid-osdfsid
- it creates and enables ceph-osd@osdid

When a node is restarted, these lvm osds are started with
- running ceph-volume@lvm-osdid-osdfsid (creating this tmpfs mount?)
- running ceph-osd@osdid


Q1: I had to create bootstrap-osd/ceph.keyring (ownership root.root). 
For what is that being used? Does it need to exist upon node restart?

Q2: I had some issues with a node starting, solving this with adding a 
nofail to the fstab. How is this done with ceph-volume?

Q3: Why these strange permissions on the mounted folder? 
drwxrwxrwt  2 ceph ceph 340 Sep 19 15:24 ceph-40

Q4: Where is this luks passphrase stored?

Q5: Where does this tmpfs+content come from? How can I mount this myself 
from the command line?

Q6: My lvm tags show ceph.crush_device_class=None, while ceph osd tree 
shows the correct class. Is this correct?

Q7: I saw in my ceph-volume output sometimes 'disabling cephx', what 
does this mean? How can I verify this and fix it?

Links to manuals are also welcome, these ceph-volume[2] are not to clear 
about this.


[1]
ceph-volume lvm create --data /dev/sdk --dmcrypt

[2]
https://docs.ceph.com/en/latest/ceph-volume/lvm/activate/