Likitha Shetty created CLOUDSTACK-8612:
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             Summary: [VMware] Make vCenter session timeout configurable for 
volume snapshot
                 Key: CLOUDSTACK-8612
                 URL: https://issues.apache.org/jira/browse/CLOUDSTACK-8612
             Project: CloudStack
          Issue Type: Bug
      Security Level: Public (Anyone can view this level - this is the default.)
            Reporter: Likitha Shetty
            Assignee: Likitha Shetty
             Fix For: 4.6.0


+Issue+
Taking a volume snapshot involves the below steps in case of VMware - 
1. Create a VM snapshot for the VM that the volume is attached to.
2. Create a VM (clone) from the snapshot disk chain of the volume to be 
snapshot'ed.
3. Export the VM created in step 2 to secondary storage.
4. Destroy the cloned VM.
5. Delete the VM snapshot taken in step 1 (This step involves VM consolidation 
in vCenter).

If any of the above steps (except VM export) takes more than 20 minutes to 
complete, snapshot backup operation will fail and the snapshot will be moved to 
'Error' state. 20 minutes because the session between CS and vCenter times out 
in 20 minutes.  

In case of VM's with large volumes (most production environments) because of 
the size of the volumes and the fact that vCenter takes too long to consolidate 
VMs this large (step 5), snapshot operation on the volume attached to this VM 
takes too long to complete even going beyond a day. 
Snapshot consolidation taking too long is a known issue with vCenter - 
[http://kb.vmware.com/selfservice/search.do?cmd=displayKC&docType=kc&docTypeID=DT_KB_1_1&externalId=1023657]

+Solution+
To work around this, CS’s session to vCenter during snapshot operation needs to 
be set to a value higher than the time taken to consolidate for the operation 
to successfully complete. But setting the existing global configuration to this 
high a value could affect all operations in the cloud and hence is not 
considered an ideal workaround.

Hence we need to split the existing vCenter session timeout configuration into 
two configurations,
1. To tune timeout value for CCP’s session vCenter during snapshot backup 
operation - _vmware.snapshot.backup.session.timeout_ (new; default: 20 minutes)
2. For all other operations - _vmware.vcenter.session.timeout_ (existing; 
default: 20 minutes)

This way setting a high timeout value for snapshot backup operation will not be 
applicable to vCenter connections made for any other operations.



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