On 01/24/2013 05:30 AM, Ugis wrote:
Hi,
I have rbd which contains non-cluster filesystem. If this rbd is
mapped+mounted on one host, it should not be mapped+mounted on the
other simultaneously.
How to protect such rbd from being mapped on the other host?
At ceph level the only option is to use "lock add [image-name]
[lock-id]" and check for existance of this lock on the other client or
is it possible to protect rbd in a way that on other clients "rbd map
" command would just fail with something like Permission denied
without using arbitrary locks? In other words, can one limit the count
of clients that may map certain rbd?
This is what the lock commands were added for. The lock add command
will exit non-zero if the image is already locked, so you can run
something like:
rbd lock add [image-name] [lock-id] && rbd map [image-name]
to avoid mapping an image that's in use elsewhere.
The lock-id is user-defined, so you could (for example) use the
hostname of the machine mapping the image to tell where it's
in use.
Josh
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