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During snapshot remove operation, a consolidate helper disk is created and the delta disks were merged to its base flat disk for asynchronous consolidate operation to allow guest OS continue to run while consolidate. But if guest performs heavy writes to disk during consolidation then consolidate helper disk grows rapidly and further to merge we create another consolidate helper disk which also grows rapidly and it goes on for 10 iterations by default and finally after 10 iterations if we cannot consolidate disks asynchronously, then we stun the VM and perform synchronous consolidation. During this time VM is stunned and guest OS will freeze and its applications are unavailable.
To stop guest OS from freezing after 10 asynchronous consolidate and to perform synchronous consolidate, VMware introduced an vmx config option "snapshot.asyncConsolidate.forceSync" in this patch and by default the value is "TRUE".
VMX config option "snapshot.asyncConsolidate.forceSync" does mean that, after asynchronous consolidate of snapshot iteration (default 10 iterations) expires, do you want to perform synchronous consolidate (TRUE) or not (FALSE).
coolgod wrote:
*does this setting automatically modified in the patch ?
No, by default vmx config option snapshot.asyncConsolidate.forceSync will set to "TRUE" even if option is not available in vmx config file of the VM and it allows snapshot consolidate to works as earlier before this patch. If you do not want to have guest OS stunned for synchronous consolidation, you should set vmx config option snapshot.asyncConsolidate.forceSync="FALSE".
coolgod wrote:
*can i modify only this setting ?
If your VM replicating software did perform snapshot remove/consolidate successfully before patch then you dont need to worry on this setting snapshot.asyncConsolidate.forceSync="FALSE".
coolgod wrote:
*when the KB says "Virtual machines might stop responding during a snapshot removal" does that mean the snapshot removal (consolidation) fails
or completes successfully?
With setting snapshot.asyncConsolidate.forceSync="FALSE" in vmx config file, after 10 asynchronous consolidate you will get an message post error "The maximum consolidate retries were exceeded." and snapshot error "The operation failed" in VI client or web client and you will end up in having one vmfs sparse disk which is a consolidate helper disk used at last iteration of asynchronous consolidate along with base disk and also virtual machine disks consolidation needed flag set and VM continues to run without freeze.
Thanks
Rajiv