Ceph: find who's mapping a RBD device

s mapping a RBD device

Curious? Wanna know who has a RBD device mapped?

W Update: Since Ceph Infernalis there is a RBD command for that

Simply run:

$ rbd status vms/2fcf7648-27d6-406f-bc92-b3f9d5ebe5f5_disk
watcher= client.15535 cookie=139998968390560

W Important note: this method only works with the Emperor version of Ceph and above.

Grab the image information:

$ rbd info boot
rbd image 'boot':
size 10240 MB in 2560 objects
order 22 (4096 kB objects)
block_name_prefix: rb.0.89ee.2ae8944a
format: 1

Then list the objects part of the pool and get the image header. Eventually run:

$ rados -p rbd listwatchers boot.rbd
watcher= client.35321 cookie=1

As we can see the machine: has the device boot mapped.