WARNING: . . . .failed verification -- update discarded (will try again).

Mac User FR macuserfr at free.fr
Thu Jun 4 08:29:49 GMT 2009

Well, when you backup a running vm disk image 3 cases may happen:

1) From the start of the copy until the end of the copy (or syncing,  
doesn't matter) the guest OS did not write anything on disk -> copy  
will be OK.
2) The guest OS write something to disk but luckily the copy process  
got all modifications (data block + catalog mods) or none of the  
modification -> the integrity of the copy will be OK, it may reflet  
the past state of the vm instead of the actual one.
3) The copy process get part of the modification by the guest, like  
only catalog info but not data blocks or inverse. Here you have no  
integrity of the disk image.

And there is another thing: data in RAM and not in disk will not be  
saved. I think in a scenario of a database always open in the guest  
OS. You will never have a working copy of those files.

You can backup from the guest OS like it was a "normal" computer. A  
basic approach that I use at the moment (lack of time to search a more  
sophisticated solution) or you can use snapshots as suggested by  
henri. I don't know what would exactly a snapshot do. A snapshot by  
the virtualization program or by the filesystem? I think if the  
snapshot is made by the virtualization program it may be safe for ram  
recovering issues, but filesystem snapshot is not. You will still need  
to save regularly open files from the guest OS.

I have absolutely no idea about the "will try again" part. Maybe Wayne  
or Matt could give you the answer.

Best regards,


Le 3 juin 09 à 23:14, JW a écrit :

> I actually have done it, and it does produce a useable copy. The  
> backup script
> does not always fail.
> Still, even if I am completely wrong about that, I still want to  
> know more
> details about the "will try again" part. When does it try again,  
> right away?
> How do I know if the re-try failed?
> 	JW
> On Wednesday 03 June 2009 15:40:44 you wrote:
>> You can't copy the disk image of a vm while the guest OS is running.
>> Best regards,
>> Vitorio
>> Le 3 juin 09 à 18:58, JW a écrit :
>>> A nightly scripted rsync backup job is giving me this error
>>> WARNING: vm/escDebLenny14G-flat.vmdk failed verification -- update
>>> discarded
>>> (will try again).
>>> I've searched the web and I think probably the problem is the source
>>> file
>>> changed during the copy.
>>> However, I haven't seen any explanations for the "will try again"
>>> part.
>>> Does it try again immediately?
>>> If so, does a  lack of further errors mean that it succeeded on the
>>> retry?
>>> Thanks,
>>> 	JW
>>> --
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>>> System Administrator - Cedar Creek Software
>>> http://www.cedarcreeksoftware.com
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