Re: [Engine-devel] [vdsm] RFC: Writeup on VDSM-libstoragemgmt integration

----- Original Message ----- > From: "Andy Grover" <agrover(a)redhat.com&gt; > To: "Shu Ming" <shuming(a)linux.vnet.ibm.com&gt; > Cc: libstoragemgmt-devel(a)lists.sourceforge.net, engine-devel(a)ovirt.org, "VDSM Project Development" > <vdsm-devel(a)lists.fedorahosted.org&gt; > Sent: Sunday, June 24, 2012 10:05:45 PM > Subject: Re: [vdsm] [Engine-devel] RFC: Writeup on VDSM-libstoragemgmt integration > > On 06/24/2012 07:28 AM, Shu Ming wrote: > > On 2012-6-23 20:40, Itamar Heim wrote: > >> On 06/23/2012 03:09 AM, Andy Grover wrote: > >>> On 06/22/2012 04:46 PM, Itamar Heim wrote: > >>>> On 06/23/2012 02:31 AM, Andy Grover wrote: > >>>>> On 06/18/2012 01:15 PM, Saggi Mizrahi wrote: > >>>>>> Also, there is no mention on credentials in any part of the > >>>>>> process. > >>>>>> How does VDSM or the host get access to actually modify the > >>>>>> storage > >>>>>> array? Who holds the creds for that and how? How does the user > >>>>>> set > >>>>>> this up? > >>>>> > >>>>> It seems to me more natural to have the oVirt-engine use > >>>>> libstoragemgmt > >>>>> directly to allocate and export a volume on the storage array, > >>>>> and > >>>>> then > >>>>> pass this info to the vdsm on the node creating the vm. This > >>>>> answers > >>>>> Saggi's question about creds -- vdsm never needs array > >>>>> modification > >>>>> creds, it only gets handed the params needed to connect and use > >>>>> the > >>>>> new > >>>>> block device (ip, iqn, chap, lun). > >>>>> > >>>>> Is this usage model made difficult or impossible by the current > >>>>> software > >>>>> architecture? > >>>> > >>>> what about live snapshots? > >>> > >>> I'm not a virt guy, so extreme handwaving: > >>> > >>> vm X uses luns 1& 2 > >>> > >>> engine -> vdsm "pause vm X" > >> > >> that's pausing the VM. live snapshot isn't supposed to do so. > > > > Tough we don't expect to do a pausing operation to the VM when live > > snaphot is undergoing, the VM should be blocked on the access to > > specific luns for a while. The blocking time should be very short > > to > > avoid the storage IO time out in the VM. > > OK my mistake, we don't pause the VM during live snapshot, we block > on > access to the luns while snapshotting. Does this keep live snapshots > working and mean ovirt-engine can use libsm to config the storage > array > instead of vdsm? > > Because that was really my main question, should we be talking about > engine-libstoragemgmt integration rather than vdsm-libstoragemgmt > integration. for snapshotting wouldn't we want VDSM to handle the coordination of the various atomic functions?

> > Thanks -- Regards -- Andy > _______________________________________________ > vdsm-devel mailing list > vdsm-devel(a)lists.fedorahosted.org > https://fedorahosted.org/mailman/listinfo/vdsm-devel > _______________________________________________ vdsm-devel mailing list vdsm-devel(a)lists.fedorahosted.org https://fedorahosted.org/mailman/listinfo/vdsm-devel