After snapshot no new changes are saved

Discussions related to using VirtualBox on Mac OS X hosts.

After snapshot no new changes are saved

Postby Krister_e » 19. Oct 2012, 23:54

Hello.

I have a somewhat of an odd issue.

After I have taken a snapshot of a virtual machine no new changes are saved to that machine.

I'm running Virtualbox 4.2.1 on Mac os X 10.8.2. The disk files are in vmdk format residing on a synology NAS connected via iSCSI.

I've created a bunch of Windows 2008 R2 Machines and everything is working good untill I take a snapshot, everything I do to the machine is not saved. I.e if I Create a new folder on the desktop and reboot, the folder is not there anymore, it is as if the snapshot makes the disk file read only. All new changes are just not commited to the disk file, so after each reboot the machine is back to the state it was in when I took the snapshot.

Has anyone noticed this issue before?

- Krister
Krister_e
 
Posts: 5
Joined: 19. Oct 2012, 23:47

Re: After snapshot no new changes are saved

Postby ChipMcK » 20. Oct 2012, 05:11

ChipMcK
Volunteer
 
Posts: 604
Joined: 20. May 2009, 02:17
Location: U S of A
Primary OS: Mac OS X other
VBox Version: PUEL
Guest OSses: Windows, Linux

Re: After snapshot no new changes are saved

Postby mpack » 20. Oct 2012, 13:16

To add to the link ChipMck provided, when you create a snapshot a difference file is created in your "Snapshots" folder and the base VDI (or VMDK) is frozen. That's how snapshots work. If you have some sort of incremental backup going on the base VMDK then of course it will see no changes.
mpack
Site Moderator
 
Posts: 13215
Joined: 4. Sep 2008, 17:09
Primary OS: MS Windows XP
VBox Version: PUEL
Guest OSses: Mostly XP

Re: After snapshot no new changes are saved

Postby Krister_e » 22. Oct 2012, 12:03

Thanks!

I know how snapshot works and the snapshot is working fine.

I was abit unclear, lets see if I can make the description abit better.

So I take a snapshot, I then proceed to Create a couple of new folders on the desktop of the machine. I reboot and then when I log back in the folders are gone.
The issue I'm having is after taking a snapshot of a system, nothing I do sticks.
Krister_e
 
Posts: 5
Joined: 19. Oct 2012, 23:47

Re: After snapshot no new changes are saved

Postby mpack » 22. Oct 2012, 13:22

In that case you may have messed up the VM settings somehow. Did you perhaps unmount and then re-mount the base VMDK in the VM (that would have replaced the snapshot current state with the base VMDK).

Otherwise the only explanation can be that something is silently restoring the folder contents - and it's hard to see how you could be unaware of that.
mpack
Site Moderator
 
Posts: 13215
Joined: 4. Sep 2008, 17:09
Primary OS: MS Windows XP
VBox Version: PUEL
Guest OSses: Mostly XP

Re: After snapshot no new changes are saved

Postby Krister_e » 22. Oct 2012, 13:48

No no unmount and remount, this happens everytime I reboot the snapshoted machines.

When I think about it my other machines, not mounted via iSCSI, does not have this issue.

So something is up with the iSCSI mount, the command i used to connect the virtual machine to the iSCSI Lun was:

"# vboxmanage storageattach Cas02 --storagectl "SATA Controller" --port 0 --device 0 --type hdd --medium iscsi --server 192.168.10.50 --target "iqn.2000-01.com.synology:Batman.name2" --tport 3260

iSCSI disk created. UUID: 02651ff0-805d-42e9-b152-800e19bfc907"

Anyone spot anything odd with the command line?
Krister_e
 
Posts: 5
Joined: 19. Oct 2012, 23:47

Re: After snapshot no new changes are saved

Postby mpack » 22. Oct 2012, 14:44

I've never used iSCSI, and I refuse to use snapshots since I see them as error prone. If you use the two together then all bets are off - I have no idea what that will do. Certainly (re)attaching a storage medium after a snapshot has been created would IMHO be likely to give rise to same problems as the mount/dismount suggestion given earlier.
mpack
Site Moderator
 
Posts: 13215
Joined: 4. Sep 2008, 17:09
Primary OS: MS Windows XP
VBox Version: PUEL
Guest OSses: Mostly XP

Re: After snapshot no new changes are saved

Postby Krister_e » 22. Oct 2012, 15:37

mpack wrote:I've never used iSCSI, and I refuse to use snapshots since I see them as error prone. If you use the two together then all bets are off - I have no idea what that will do. Certainly (re)attaching a storage medium after a snapshot has been created would IMHO be likely to give rise to same problems as the mount/dismount suggestion given earlier.


Well I guess that is the differance between paid solutions and free solutions :) Snapshots that works are really good for like lab enviroments where you want to test out different scenarios without rebuilding everything everytime.

No quite sure why you are talking about attaching/mounting/dismounting, i'm not doing anything of that. Anyway, i'll have to continue but without snapshots :(
Krister_e
 
Posts: 5
Joined: 19. Oct 2012, 23:47

Re: After snapshot no new changes are saved

Postby ChipMcK » 22. Oct 2012, 20:08

Krister_e wrote: the command i used to connect the virtual machine to the iSCSI Lun was:

"# vboxmanage storageattach Cas02 --storagectl "SATA Controller" --port 0 --device 0 --type hdd --medium iscsi --server 192.168.10.50 --target "iqn.2000-01.com.synology:Batman.name2" --tport 3260

iSCSI disk created. UUID: 02651ff0-805d-42e9-b152-800e19bfc907"
What happens if you should the the attach via the GUI?
Also, the --target parameter appears to be the base vdi, not the differencing VDI.
What happens if you specify the differencing disk?
ChipMcK
Volunteer
 
Posts: 604
Joined: 20. May 2009, 02:17
Location: U S of A
Primary OS: Mac OS X other
VBox Version: PUEL
Guest OSses: Windows, Linux

Re: After snapshot no new changes are saved

Postby Krister_e » 23. Oct 2012, 10:04

ChipMcK wrote:
Krister_e wrote: the command i used to connect the virtual machine to the iSCSI Lun was:

"# vboxmanage storageattach Cas02 --storagectl "SATA Controller" --port 0 --device 0 --type hdd --medium iscsi --server 192.168.10.50 --target "iqn.2000-01.com.synology:Batman.name2" --tport 3260

iSCSI disk created. UUID: 02651ff0-805d-42e9-b152-800e19bfc907"
What happens if you should the the attach via the GUI?
Also, the --target parameter appears to be the base vdi, not the differencing VDI.
What happens if you specify the differencing disk?


Well in my world, when I create a new virtual machine I attach a disk over iSCSI that virtualbox can use for storing data. When I do a snapshot I assume that virtualbox will take care of the innerworkings for me, I.e I should not need to do anything other then create a snapshot and then do what I want to do with the machine. If I want to revert back I simply tell virtualbox to revert the snapshot and all my changes are undone.

My command above was run when I created the machine, as far as I'm aware I cannot attach an iSCSI disk in the gui without first making the connection with the command line.

Are you saying that after I create a snapshot I need to disconnect the LUN and try to Attach the snapshot? cause that sounds crazy to me :)
Krister_e
 
Posts: 5
Joined: 19. Oct 2012, 23:47

Re: After snapshot no new changes are saved

Postby ChipMcK » 23. Oct 2012, 15:07

Could it be that you are the only OS X user using iSCSI?
What happens if --target specifies the differencing disk?
ChipMcK
Volunteer
 
Posts: 604
Joined: 20. May 2009, 02:17
Location: U S of A
Primary OS: Mac OS X other
VBox Version: PUEL
Guest OSses: Windows, Linux

Re: After snapshot no new changes are saved

Postby rshaw » 21. Feb 2013, 01:31

I have run into this exact problem and found this post through searching, but I am running on a Linux host (has nothing to do with OSX)

I have filed a bug report.

https://www.virtualbox.org/ticket/11479
rshaw
 
Posts: 15
Joined: 11. Feb 2013, 17:04

Re: After snapshot no new changes are saved

Postby klaus » 3. May 2013, 18:19

The bug report is lacking a VBox.log file - if anyone who sees this issue could attach such a log to the ticket then it'd be a lot simpler to reproduce (and make sure that your VM config gets tested)...
klaus
Oracle Corporation
 
Posts: 234
Joined: 10. May 2007, 14:57

Re: After snapshot no new changes are saved

Postby klaus » 6. May 2013, 17:41

Issue is resolved, and reporter confirmed. Will be included in VirtualBox 4.2.14. Until then the fix is available on request since there are apparently extremely few people using the affected VM configurations.
klaus
Oracle Corporation
 
Posts: 234
Joined: 10. May 2007, 14:57

Re: After snapshot no new changes are saved

Postby wilgin » 11. Jun 2013, 20:27

hello,
hope the new Version with the fix for differncing disks will publish soon. i´m waiting for this Feature
actually i use Hyper-V to work with many VMs based on one Image

best regards
Wilfried
wilgin
 
Posts: 2
Joined: 15. Feb 2011, 13:05
Primary OS: MS Windows Vista
VBox Version: OSE Debian
Guest OSses: 1


Return to VirtualBox on Mac OS X Hosts

Who is online

Users browsing this forum: Google [Bot] and 12 guests