On Thu, Feb 24, 2022 at 3:58 PM Nir Soffer <nsof...@redhat.com> wrote:
> On Wed, Feb 23, 2022 at 6:24 PM Muli Ben-Yehuda <m...@lightbitslabs.com> > wrote: > > > > Thanks for the detailed instructions, Nir. I'm going to scrounge up some > hardware. > > By the way, if anyone else would like to work on NVMe/TCP support, for > NVMe/TCP target you can either use Lightbits (talk to me offline for > details) or use the upstream Linux NVMe/TCP target. Lightbits is a > clustered storage system while upstream is a single target, but the client > side should be close enough for vdsm/ovirt purposes. > > I played with NVMe/TCP a little bit, using qemu to create a virtual > NVMe disk, and export > it using the kernel on one VM, and consume it on another VM. > https://futurewei-cloud.github.io/ARM-Datacenter/qemu/nvme-of-tcp-vms/ > > One question about device naming - do we always get the same name of the > device in all hosts? > No, we do not, see below how we handle migration in os_brick. To support VM migration, every device must have unique name in the cluster. > With multipath we always have unique name, since we disable "friendly > names", > so we always have: > > /dev/mapper/{wwid} > > With rbd we also do not use /dev/rbdN but a unique path: > > /dev/rbd/poolname/volume-vol-id > > How do we ensure cluster-unique device path? If os_brick does not handle > it, we > can to do in ovirt, for example: > > /run/vdsm/mangedvolumes/{uuid} -> /dev/nvme7n42 > > but I think this should be handled in cinderlib, since openstack have > the same problem with migration. > Indeed. Both the Lightbits LightOS connector and the nvmeof connector do this through the target provided namespace (LUN) UUID. After connecting to the target, the connectors wait for the local friendly-named device file that has the right UUID to show up, and then return the friendly name. So different hosts will have different friendly names, but the VMs will be attached to the right namespace since we return the friendly name on the current host that has the right UUID. Does this also work for you? Cheers, Muli -- *Lightbits Labs** *Lead the cloud-native data center transformation by delivering *scalable *and *efficient *software defined storage that is *easy *to consume. *This message is sent in confidence for the addressee only. It may contain legally privileged information. The contents are not to be disclosed to anyone other than the addressee. Unauthorized recipients are requested to preserve this confidentiality, advise the sender immediately of any error in transmission and delete the email from their systems.*
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