Ceph: find who'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
Watchers:
        watcher=192.168.0.41:0/3263847771 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=192.168.251.102:0/2550823152 client.35321 cookie=1

As we can see the machine: 192.168.251.102 has the device boot mapped.

Sébastien Han

Ceph: find who's mapping a RBD device

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