Here is the link to the corresponding FS (placed in “4.5 Design documents” 
section)

https://cwiki.apache.org/confluence/display/CLOUDSTACK/ROOT+volume+detach

-Alena.

From: Alena Prokharchyk 
<alena.prokharc...@citrix.com<mailto:alena.prokharc...@citrix.com>>
Date: Monday, March 24, 2014 at 11:37 AM
To: "dev@cloudstack.apache.org<mailto:dev@cloudstack.apache.org>" 
<dev@cloudstack.apache.org<mailto:dev@cloudstack.apache.org>>
Subject: [PROPOSAL] ROOT volume detach - feature for CS 4.5

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.

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