Hi Jason, > > 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. > The way we orchestrate the RBD volumes today makes it difficult to do it the way k8s CSI does. Volume map and unmap are currently managed by individual hypervisor threads/subprocesses so we just keep a 1:1 mapping of devices to containers. Thanks, Shridhar > > >> >> 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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