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VM is different after TimeMachine restore
Posted: 14. Feb 2013, 19:35
by layman
Hello,
I had a double (!) hard drive crash

and had to restore my MacMiniServer from Apple TimeCapsule / TimeMachine. Host system is MacOS 10.6 Server, guest is WindowsServer2003. Both servers ran uninterrupted since the first days of January.
After restoring MacServer and VirtualBoxMachine worked

but the virtual machine has become the old state from the first days of January

all data of the last weeks are missing
There are no snapshots displayed (I think there was none).
How can I get my machine at the actual state? What was the mistake producing an "old" machine?
Thank You
layman - newbie with virtualization
Re: VM is different after TimeMachine restore
Posted: 14. Feb 2013, 19:45
by Perryg
Backups are only as good as the last time they were actually run. From the sounds of it you have not updated the backup. I am not a Mac guru but I would think that would be a configurable step. In any case I see this as a host OS issue and you probably will get better answers from a Mac forum.
Re: VM is different after TimeMachine restore
Posted: 14. Feb 2013, 19:55
by layman
Sorry, but I don't think so: The backup is dated some hours before the crash, the guest-Server restored at that actual state. So should VirtualBox do.
Only my Virtual Machine is at an old state - running, but antique. I think that is a VirtualBox releated problem.
Thank You
layman
Re: VM is different after TimeMachine restore
Posted: 14. Feb 2013, 20:02
by Perryg
I can only say this. A backup is only as good as the last time it was run and add that it should include all files. If you use snap shots then these must be restored as well, and the VirtualBox control files. The VirtualBox.xml (master) an the *.vbox.
You time machine is responsible for the backup so how would that be a VirtualBox issue?
Re: VM is different after TimeMachine restore
Posted: 14. Feb 2013, 20:10
by layman
When a virtual machine runs for a longer time and no snapshots are made, the difference between start-state and later-state, the "difference" must be stored somewhere. I think there probably is a special file for that.
I'm searching for this (missing or not found?) file to tell my virtual machine the difference in between old and actual state.
Re: VM is different after TimeMachine restore
Posted: 14. Feb 2013, 21:35
by ChipMcK
Time Machine was designed to backup documents after creating and after editing.
Time Machine was NOT designed to backup documents while the document is being edited.
Various editors have auto-save feature/facility for backup of the document in the midst of editing, replacing the entire document upon closing.
VirtualBox, like the other virtualisers, is based on the "document template".
When a virtual machine is running or active, it is being edited - the virtual disk is open and being altered. Time Machine can NOT produce a valid backup of an open document. If the document (virtual disk) has been split into files of less than 2GB, any individual file at any given moment may be closed and Time Machine, during a time slice, may backup that individual file before it is edited with the 'current' data.
While most virtualisers have a snapshot feature/facility, none are a full functional auto-save. They create only a delta update to the virtual disk, not a replacement. The user is required to cause the replacement of the virtual disk by the merging of the snapshot updates with the 'base' virtual disk.
Time Machine backups are not dependable unless the virtual machine has been shutdown.
A backup of saved-state virtual machine is iffy IMHO, as Time Machine may NOT have backed up the full configuration of files comprising a virtual machine during a single time slice.
Comments/Opinions?
Updated: to correct grammar and typos
Re: VM is different after TimeMachine restore
Posted: 14. Feb 2013, 22:29
by noteirak
ChipMcK wrote:Comments/Opinions?
You are right, and this is a general backup problem for many all virtualization product and many other software, like DB, Active Directory & so on.
That's also why VSS (Microsoft Shadow Copy) was born per example.