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data reverted to old versions after creating new vm

Posted on 2011-09-30
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Last Modified: 2012-05-12
we have created a new vm and linked the hdd's to another vm's disks which has been powered off, when the new vm was powered on the files on the vm were out-of-date. how do we get the data back to the way it was i.e. up-to-date? we can restore the vm from backup but, the folder we need is missing from the backup.
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Question by:loughtec
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Expert Comment

by:mkrohn
ID: 36893124
Hi,
It looks like you use an old snapshot copy of your old VM.
I would turn off the new VM, turn on the old VM and see if you have snapshots.
If you have snapshots, try to delete the old ones, to cleanup and see what are the files that stores the info you need

best regards
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LVL 119
ID: 36893134
"another vm's disks which has been powered off."

did this another VM, have snapshots attached to the disks?

It possible, you have connected the disks to another VM, powered on, but this VM does not know about the Snapshots attached to the disks, that the "another VM" had!

Check the Snapshot Manager on the "another VM".

It's likely now, as you have powered on without it knowing about the snapshots, you have caused further issues, as the old "another VM" will not power on without error!
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Author Comment

by:loughtec
ID: 36893175
there was a snapshot in the old vm folder also which is dated the time that the info has rolled back to. I have removed this and restarted the vm but, the data is still old. i sthere any way of recovering? datastore
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Author Comment

by:loughtec
ID: 36893243
vmx file attached.
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Author Comment

by:loughtec
ID: 36893247
vmx file attached.
mcsapps1vmx.txt
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LVL 119
ID: 36893350
The data is still old?

do mean not up to date missing?

how did you delete the snapshots? just by deleting the file?
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LVL 119
ID: 36893354
I meant, data missing?
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Author Comment

by:loughtec
ID: 36893365
hi, sorry i mean not up to date. data is still showing as old when server is booted.

i removed the snapshot via snapshot manager.
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LVL 119
ID: 36893369
You may want to read over this to understand Snapshots better.

A snapshot is NOT a backup of a VM; that is a gross misconception.  

A snap shot is a way to preserve a point in time when the VM was running OK before making changes. A snapshot is NOT a way to get a static copy of a VM before making changes.  When you take a snapshot of a VM what happens is that a delta file gets created and the original VMDK file gets converted to a Read-Only file.  There is an active link between the original VMDK file and the new delta file.  Anything that gets written to the VM actually gets written to the delta file.   The correct way to use a snapshot is when you want to make some change to a VM like adding a new app or a patch; something that might damage the guest OS. After you apply the patch or make the change and it’s stable, you should really go into snapshot manager and delete the snapshot which will commit the changes to the original VM, delete the snap, and make the VMDK file RW. The official stance is that you really shouldn’t have more than one snap at a time and that you should not leave them out there for long periods of time. Adding more snaps and leaving them there a long time degrades the performance of the VM.  If the patch or whatever goes badly or for some reason you need to get back to the original unmodified VM, that’s possible as well.  

I highly recommend reading these 2 articles on VMware Virtual Machine Snapshots:

Understanding Snapshots - http://kb.vmware.com/kb/1015180
Snaphot Best Practices - http://kb.vmware.com/kb/1025279

Also check out the following Snapshot Articles by Eric Siebert

Pt.1- http://is.gd/Lajg4p
Pt.2- http://is.gd/NdKQWC
Pt.3- http://is.gd/tp2vEK
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LVL 119
ID: 36893382
If your Server is out of date and missing data, or out of date.

All the updates have gone, when your removed the Snapshot files.

The recent changes will be in the Snapshot files, which should have been comitted to disk, which would have merged the snapshot delta files with the main virtual disk, giving you an updated virtual disk, with all your recent changes.

So I think your data is lost.
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Author Comment

by:loughtec
ID: 36893459
i dont think the snapshot is the problem, i think maybe the new vm might have been mapped wrong to the disks in the other vm folder?
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Author Comment

by:loughtec
ID: 36893465
hi, the snapshot file was tiny and we are talking about a 7/8 month roll back.
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LVL 119
ID: 36893485
there was a snapshot, all changes would have been written to the snapshot.

the snapshot sizes were 2GB and 17GB worth of changes, since put into snapshot mode.

As you have deleted the snapshot I cannot advise your further on recovery of the machine.

Snapshot should not have been deleted, after powering on the new VM without knowing about the existence of snapshot disk.
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Author Comment

by:loughtec
ID: 36893693
on checking, those 2gb and 17gb files have actually been created by the acronis backup software while backing up the server.
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LVL 119

Accepted Solution

by:
Andrew Hancock (VMware vExpert / EE MVE^2) earned 500 total points
ID: 36893729
Yes, Acronis and ALL third party backup products, use the Storage APIs to put the VM into Snapshot Mode (it dose not create them). At that moment all data is written to the snapshot files, so the backup application can backup the main VMDK file, because the Machine Lock has been removed from the file. At the end, the Backup Application is supposed to Committ/Merge and close the Snapshot file.

BUT, it's the FAILURE of ALL third party backup products that they do not do this (all the time), so you VM, carries on writing to the Snapshot Delta file 1) this is causes performance problems, 2) dangerous position, because datastores can fill up 3) get corrupted 4) VMware Admins do not understand snapshots, and mess up the VM!

Once a machine is in Snapshot Mode, it writes to the delta file. Please refer to above post, which explains snapshots.
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Author Comment

by:loughtec
ID: 36896296
i have the snapshot vmsn file back in but, when i power on the machine i get The parent virtual disk has been modified since the child was created. would you be able to help here?
Capture.JPG
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LVL 119
ID: 36896321
Yes, as I suspected this would happen, if the disks were powered on, on another VM.

and then you retried on the original.

There is a procedure that can be followed:-

Check here

http://kb.vmware.com/kb/1007969
http://edgylogic.com/driveactivated/recovering-vmware-snapshot-after-parent-changed/
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Author Comment

by:loughtec
ID: 36896436
being stupid here (not 100% on this) but, if my physical disks are in the server how can i open vmdk with editpad liet, 010 editor etc... do i need to download the vmdk files first as that will take days probably. i have never used linux commands.
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Author Comment

by:loughtec
ID: 36896444
dont suppose you freelance and want to help out hanccocka :)
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LVL 119
ID: 36896523
Contact through Profile.
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LVL 119
ID: 36896539
Please also not there is no guarantee that you will get the data back, it's possible that the data maybe lost.

If the data is important and you have no backup, I would consider contacting a Data Recovery Specialist.

e.g.Kroll Ontrack
http://www.krollontrack.co.uk/
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LVL 119
ID: 36896544
you edit the files on the ESX server.
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Author Comment

by:loughtec
ID: 36896722
sent you a message on your profile, when do you think you can check files for me?
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Author Closing Comment

by:loughtec
ID: 36943029
had to get vmware invloved to clone base disks and delta files
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