rsync - Jun 2009 - WARNING: . . . .failed verification -- update discarded (will try again).

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

-- 

----------------------
System Administrator - Cedar Creek Software
http://www.cedarcreeksoftware.com

You can't copy the disk image of a vm while the guest OS is running.

Best regards,

Vitorio

Le 3 juin 09 ? 18:58, JW a ?crit :
> 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
>
> -- 
>
> ----------------------
> System Administrator - Cedar Creek Software
> http://www.cedarcreeksoftware.com
> -- 
> Please use reply-all for most replies to avoid omitting the mailing  
> list.
> To unsubscribe or change options:
https://lists.samba.org/mailman/listinfo/rsync
> Before posting, read: http://www.catb.org/~esr/faqs/smart-questions.html

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,

Vitorio

Le 3 juin 09 ? 23:14, JW a ?crit :
> 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 ? 18:58, JW a ?crit :
>>> 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
>>>
>>> --
>>>
>>> ----------------------
>>> System Administrator - Cedar Creek Software
>>> http://www.cedarcreeksoftware.com
>>> --
>>> Please use reply-all for most replies to avoid omitting the mailing
>>> list.
>>> To unsubscribe or change options:
>>> https://lists.samba.org/mailman/listinfo/rsync Before posting,
read:
>>> http://www.catb.org/~esr/faqs/smart-questions.html
>
>
>
> -- 
>
> ----------------------
> System Administrator - Cedar Creek Software
> http://www.cedarcreeksoftware.com

JW (jw@mailsw.com) wrote on 3 June 2009 11:58:
 >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?

After pulling a file rsync verifies its checksum; if it fails rsync
tries once more, and if it still fails rsync gives up and reports the
error. Therefore if there is no final error message the file was
successfully pulled.

This is explained in http://rsync.samba.org/how-rsync-works.html

Here is the mail from henri.
Best regards,

Vitorio

D?but du message r?exp?di? :
> De : henri <henri@stmargarets.school.nz>
> Date : 4 juin 2009 00:30:32 HAEC
> ? : Mac User FR <macuserfr@free.fr>
> Objet : R?p : WARNING: . . . .failed verification -- update  
> discarded (will		try again).
>
> I was going to write a daemon to manage suspend and resume of VM  
> images during backups. After designing the system (on paper - not in  
> code) I realized that this system was probably not required for  
> dealing with VM backups.
>
> The reason I came to this conclusion was because I realized I could  
> just enable auto-protect (automated snapshots of the VM) and then  
> backup the live VM. Is this not the case?
>
> Any information or experiences would be very helpful. I would be  
> particularly interested to know if anyone backed up running VM and  
> then had issues rolling back to a known good snap-shot?
>
> Maybe the design (still in my draw) will actually be of some use?
>
> Thanks.
Le 5 juin 09 ? 00:42, JW a ?crit :
> On Thursday 04 June 2009 03:29:49 you wrote:
>> r 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.
>
> Thank you for taking the time to answer. As an aside, I did not  
> receive any
> emails from "henri" and i don't see any on the list - what
did he
> say? I'm
> sure he's talking about VM snapshots, not FS. I am aware of the  
> issues you
> raised and I do, in fact, backup the internal contents of the Guest  
> OS. But I
> also backup the actual VM disk-image-files because recreating VMs from
> scratch is not fun - I can usually use the backup, and then
"restore"
> whatever data might be missing "inside" the VM guest OS. At least
> the main
> system setup is preserved.
>
> In other words, it's a third-level backup just to save me  time in  
> the event
> of catastrophic failure. I also have an original copy of the VM from  
> when it
> was first created (and that backup was made with the VM  guest  
> powered off).
>
>> I have absolutely no idea about the "will try again" part.
Maybe
>> Wayne
>> or Matt could give you the answer.
>
> Carlos' answer was pretty good. Thank you.
>
> 	JW
>
> -- 
>
> ----------------------
> System Administrator - Cedar Creek Software
> http://www.cedarcreeksoftware.com