Most of you probably knew that it is impossible to snapshot an independent/persistent disk. And if you didn’t, in short: a disk that is in “independent/persistent” mode can’t be snapshot because it needs to write it’s changes immediately to the virtual harddisk. When using a snapshot(nonpersistent) writes go to a delta file.
So as I said in this article, using this mode on a specific disk is a nice way to get the full image VM without for instance that gigantic data disk. But some of you might need the snapshot functionality, and it’s not possible to change the disk state from the VirtualCenter client when the VM is up and running.
But it is possible to change the state via the command-line when the VM is running. So if you want to change the state in a VCB script for a specific disk, or want to change the state for a VM without shutting it down here you go:
Find out what the current mode is from the command line:
vmware-cmd <path to vmx file.vmx> getconfig scsi0:0.mode
Set the new mode from the command line:
vmware-cmd <path to vmx file.vmx> setconfig scsi0:0.mode “persistent”
Keep in mind that this is, as far as I know, not supported and should be tested thoroughly before using. I would prefer doing it manually and keeping it that way. Or you could always use the script that I blogged about a while back, it makes it possible to dump specific disks without having to resort to unsupported methods.
By the way, with the setconfig option you can set most vmx options!