Hey Bill, Thanks for getting back to me.
If I'm understanding you correctly, you're basically using the ssh transfer manager to perform live migrations? Do you then create/mount one rbd per host? E.g., host1: mount /dev/rbd/rbd/host1-one-system /var/lib/one/datastores/0 host2: mount /dev/rbd/rbd/host2-one-system /var/lib/one/datastores/0 then use the modified ssh drivers to perform the migrations? I would definitely be interested in learning how you accomplished that. My other thought was to use CephFS for shared storage. This would eliminate the need for a NFS/GlusterFS/CLVM, which is an extra layer of complexity I would like to avoid. As I understand it though, CephFS isn't "ready for prime-time" which gives me pause... Thanks again, Jon A On Tue, Jul 9, 2013 at 7:55 PM, Campbell, Bill < bcampb...@axcess-financial.com> wrote: > Jon, > I think I understand what you are trying to do, but I think it doesn't > quite work that way. Let me try to explain (and please let me know if I > don't explain it well enough ;-)) > > I don't think that you can use Ceph directly as a system datastore. The > way the Ceph datastore driver works for migrations is leveraging whatever > transfer method you have for the system datastore to perform the migration. > For example, if you use the 'shared' system datastore, then it will use > that transfer manager's pre and post migration drivers. For 'ssh', the ssh > drivers, and so on. The way the Ceph datastore is implemented is as Ceph > Block Devices, so unfortunately there is not a way to use it as a simple > shared volume. > > There are 2 potential solutions for getting live migrations working for > your Ceph datastore VMs: > > - Create a shared NFS volume (or other 'sharable' filesystem, like > GFS2, OCFS2, etc., however these are much more complicated to configure and > usually not worth the hassle) and have the shared volume mounted to the > same location on each hypervisor node. In a previous test deployment, we > just exported out the /var/lib/one/vms directory to the hypervisors. At > this point, all of the hypervisors should be able to see the deployment > files in the same location and you should be able to perform a migration. > - Use SSH as the transfer manager for your system datastore, and > modify the pre and post-migrate scripts to copy the deployment files from > the current VM host to the target VM host. This is the method we use > currently in our deployment, as it is one less configuration step that we > have to worry about maintaining on each node, and makes expanding our > cluster much quicker and easier. I can share with you the pre and > post-migrate scripts we use if you like. > > Let me know if the above makes sense, and of course if you need any > additional help please don't hesitate to bug me. I'm very familiar with > the Ceph drivers ;-) > > ------------------------------ > *From: *"Jon" <three1...@gmail.com> > *To: *"Users OpenNebula" <users@lists.opennebula.org> > *Sent: *Tuesday, July 9, 2013 8:05:51 PM > *Subject: *[one-users] How to use Ceph/RBD for System Datastore > > > Hello All, > > I am using Ceph as my storage back end and would like to know how to > configure the system datastore, such that I can live migrate vms. > > Following the directions, I thought I could create a datastore, format it, > and mount it at /var/lib/one/datastores/0 , however, I discovered, that > isn't quite how things work. > > >> > http://lists.ceph.com/pipermail/ceph-users-ceph.com/2013-May/001913.html > You can read more about that at the above link, but long story short, to > mount a shared filesystem it has to be a "clustered" filesystem (I think > CephFS is the "clustered filesystem", in this case). > > I attempted to modify my system datastore config, however, I was unable to > change the DS_MAD parameter, and vm creation errors out telling me there's > no /var/lib/one/remotes/tm/ceph/mkswap driver (there isn't) > > >> oneadmin@red6:~$ onedatastore show 0 > >> DATASTORE 0 INFORMATION > > >> ID : 0 > >> NAME : system > >> USER : oneadmin > >> GROUP : oneadmin > >> CLUSTER : - > >> TYPE : SYSTEM > >> DS_MAD : - > >> TM_MAD : ceph > >> BASE PATH : /var/lib/one/datastores/0 > >> DISK_TYPE : FILE > >> > >> PERMISSIONS > > >> OWNER : um- > >> GROUP : u-- > >> OTHER : --- > >> > >> DATASTORE TEMPLATE > > >> DISK_TYPE="rbd" > >> DS_MAD="-" > >> TM_MAD="ceph" > >> TYPE="SYSTEM_DS" > >> > >> IMAGES > > Maybe I'm just confused. Can anyone provide some guidance on setting ceph > up as the system datastore? > > Thanks, > Jon A > > _______________________________________________ > Users mailing list > Users@lists.opennebula.org > http://lists.opennebula.org/listinfo.cgi/users-opennebula.org > > > *NOTICE: Protect the information in this message in accordance with the > company's security policies. If you received this message in error, > immediately notify the sender and destroy all copies.* > >
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