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  • 1.  Snapshot consolidation of Virtual Machine on NFS

    Posted Aug 09, 2021 03:49 PM

    Hi,

    If VM is on NFS and consolidate disks is needed. What happens, do the changes have to travel over the NFS network so that the vmdk's are consolidated into one vmdk or is it done on the NFS backend without any Host involvement?

    Guess also any big changes taken place whilst VM remains on will need to be picked up at the end once the consolidation is over?

    If consolidation fail, would a shut of the VM be the next step and try again after? (Or maybe creating another snapshot and try to delete but just do not want to make things worse, ie: more disks

     

    Thanks



  • 2.  RE: Snapshot consolidation of Virtual Machine on NFS
    Best Answer

    Broadcom Employee
    Posted Aug 22, 2021 02:10 AM

    Hi,

    Essentially the work is performed by the host. unless you have "array" level snapshots; which would not show up in the VMware snapshot tab in vCenter.

    The snapshot data would be read and replayed back into the "base" disk; via a mirror driver mechanism.

    Depending on your version of esxi the technology has changed; newer versions of ESXi actually will get better performance if the VM is left powered on, but in guest operations are limited.. so for example a VM that is just sitting there in windows, will perform faster than a vm with database services running.

    Depending on the amount of in guest IO an offline consolidation may be faster, but that is rare on newer version of ESXi.

    As I said the technology has changed and the way consolidation occurs no longer needs new snapshots to be created, during consolidation, changes that occur during the consolidation time are now written directly to the base disk.

    The change happened with vSphere 6; so most supported versions should be using the new technology.

    The consolidation is unlikely to fail, but if it does, repeating the attempt will do no harm, and powering off the VM will mean a slower data through put, and that the task must complete before the VM can be powered on again.

    If it doesn't complete, My personal favorite option is to clone the VM when it is powered off. This will consolidate the snapshot chain and clear the issues, or if there is an underlaying issue that is causing the failure (bad disk sector etc) then using vmware converter may still get you out of a jam.. it is an old out of support product, but this is a lab machine right?!?!? if it was important you would have a backup right!?!?!?!?!



  • 3.  RE: Snapshot consolidation of Virtual Machine on NFS

    Posted Aug 24, 2021 06:19 AM

    useful info thanks, it eventually worked after stopping most of the I/O operations at the operating System level