Thanks Ilya. The challenge is that, in our environment, we could have multiple containers using the same volume on the same host, so we map them multiple times and unman them by device when one of the containers complete/terminate - so that we dont unmap the one that's still in use by other container. Is it possible to add custom udev rules to control this behavior? Thanks, Shridhar On Mon, 20 Apr 2020 at 01:19, Ilya Dryomov <idryomov@gmail.com> wrote:
On Sat, Apr 18, 2020 at 6:53 AM Void Star Nill <void.star.nill@gmail.com> wrote:
Hello,
How frequently do RBD device names get reused? For instance, when I map a volume on a client and it gets mapped to /dev/rbd0 and when it is
unmapped,
does a subsequent map reuse this name right away?
Yes.
I ask this question, because in our use case, we try to unmap a volume
we are thinking about adding some retries in case unmap fails for any reason. But I am concerned about race conditions such as the following: 1. thread 1 calls unmap, but the call times out and returns in the
but in the background unmap request does go through and the device gets removed 2. thread 1 does a retry based on the device name.
If between 1 and 2, another thread tries to map another volume and if it gets mapped to same device right after previous unmap was successful,
and process, then
in step 2, we will be trying to unmap a device that doesn't belong to previous map.
So I want to know how frequently do the device names get reused, and if there is a way to keep them using new names until they round back after a max limit.
No, there is no way.
Use image names instead of device names, i.e. "rbd unmap myimage" instead of "rbd unmap /dev/rbd0".
Thanks,
Ilya