On Mon, Apr 20, 2020 at 1:20 PM Void Star Nill <void.star.nill@xxxxxxxxx> wrote: > 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. > Why would you need to map the same image multiple times? Is that just a limitation of your container management system? For example, k8s w/ ceph-csi will only map a PVC once per node even if it's used by multiple containers. When the last container is stopped, it will then unmap the image. > > 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@xxxxxxxxx> wrote: > > > On Sat, Apr 18, 2020 at 6:53 AM Void Star Nill <void.star.nill@xxxxxxxxx > > > > 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 > > and > > > 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 > > process, > > > 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, > > 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 > > > _______________________________________________ > ceph-users mailing list -- ceph-users@xxxxxxx > To unsubscribe send an email to ceph-users-leave@xxxxxxx > > -- Jason _______________________________________________ ceph-users mailing list -- ceph-users@xxxxxxx To unsubscribe send an email to ceph-users-leave@xxxxxxx
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