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

[Andy Grover]

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"
engine -> libstoragemgmt "snapshot luns 1, 2 to luns 3, 4"
engine -> vdsm "snapshot running state of X to Y"
engine -> vdsm "unpause vm X"
engine -> vdsm "change Y to use luns 3, 4"

?

-- Andy