What is not quite right in CS at the moment - instead of relying on the device id=0 for determining if the volume is ROOT, we mark the volume with type datadisk/root in the DB. Ideally we should be more flexible, and volume should have no type tight to it as it can be DataDisk or Root disk depending on its placement.
Considering the above, I was planning to implement feature the following way: 1) Once volume is detached, its type is changed to DataDisk. 2) Once volume gets attached to the device 0 of the vm, it becomes a ROOT disk. If volume gets attached to any other device, its type remains to be DataDisk. On 3/24/14, 11:55 AM, "Marcus" <shadow...@gmail.com> wrote: >Yes, I think we need a call to change disk type between data and root > >On Mon, Mar 24, 2014 at 12:37 PM, Alena Prokharchyk ><alena.prokharc...@citrix.com> wrote: >> I would like to propose a new feature for CS 4.5 - "ROOT volume detach" >>- that enables support for following use cases: >> >> 1) Replace current ROOT volume with the new one for existing vm. >> 2) Case when ROOT volume of vm1 gets corrupted, and you want to attach >>it to vm2 to run the recovery utils on it. With current CS >>implemntation, you have to perform several steps - create snapshot of >>vm1's volume, create volume from snapshot, attach volume to the vm2. New >>implementation will merge it all to one step. >> >> >> With the planned implementation, once the ROOT volume is detached, it >>can be attached to any existing vm (with respect to >>Admin/Domain/Physical resources limitations), either as a DataDisk or a >>Root disk. >> >> Amazon EC2 already has this functionality in place, so I think CS would >>only benefit from having it. Storage experts (Edison, others) please >>raise your concerns if you have any, or if you see any potential >>problems with the planned implementation. And if anyone can think of >>other use cases this feature can possible solve, I would appreciate this >>input as well. >> >> >> Feature limitations: >> >> * ROOT volume can be detached only when vm is in Stopped state >> * CS will fail to start the vm not having a ROOT volume >> >> I will send out the link to the FS once I start getting feedback on the >>proposal. >> >> -Alena.
