Hello, On Wed, Feb 27, 2008 at 07:40:26PM +0000, Rodrigo Ventura wrote: > On Feb 27, 2008, at 7:00 PM, Patrick M. Hausen wrote: > >> Does anyone know the reason why you cannot snapshot powered off >> machines? > > > Hum, only the obvious answer pops to mind: because there is no state to > snapshot at all! A powered-off machine has no state, besides the contents > of the harddrive (vmware: the disk image) and of the NVRAM (vmware: stored > in some file, together with the vmware config). So, if you backed up the > virtual machine directory (containing the disk image, config and NVRAM), I > guess you are all set. Nothing else exists in a real physical computer > anyway...
Correct. But as I understand, snapshots in VMware work similar to transaction logs in databases. The virtual disk file is locked in its current state and further changes are temporarily written to separate files until the snapshot is comitted or rolled back. So if you want to backup/copy an entire VM with the guarantee of consistent hard disk state, you need to shut it down. Copying a multi gigabyte virtal disk file is bound to take quite some time. So you need to power down your virtual machine for what can amount to hours. Compare: power down lock virtual hard disk boot writing all changes to separate transaction log instead of vdisk VM runs and provides service while you can backup the vdisk ... commit snapshot after backup is done You can do something at least similar with Linux/Unix VMs: boot into single user mode (fs mounted read-only) take snapshot boot multiuser do backup while running multiuser commit snapshot when backup is done Regards, Patrick -- punkt.de GmbH * Vorholzstr. 25 * 76137 Karlsruhe Tel. 0721 9109 0 * Fax 0721 9109 100 [EMAIL PROTECTED] http://www.punkt.de Gf: Jürgen Egeling AG Mannheim 108285
