What exactly is "Application aware processing" ?

[wessel@RUC]

Hello Guys and Experts
- I just upgraded VBR at our University from 9.5 to ver 10.
Everything seems okay, EXCEPT i found out, we still have some old 2003 servers due to some old troublesome apps on a DC. Yes, i know .. doesn't quite make sense, but thats the case.
Anyways, after upgrading Backup job fails regarding these 2003 servers, i get the message: "Failed to prepare guest for hot backup. Error: Unable to perform application-aware processing: Microsoft Windows Server 2003 (Enterprise) guest OS is not supported "

I searched through the manual, but dont get any hits to understand what exactly this enabled settings does, and if its safe to disable, and what exactly i will be disabling if i chose to uncheck "Application aware processing" , as it will also influence other servers in the same job.

Thank you in advance.

[HannesK]

Hello,
Veeam application aware image processing creates a VSS snapshot (volume shadow copy services) + Veeam proprietary backup & restore functionality. VSS is a Microsoft technology to ensure application consistency.

You can disable it for the whole job, or you can disable it for the 2003 machines in the Applications settings. Just add the VM in the next screen and disable application processing for the legacy machines

Well, for the 2003 domain controller... if it is a multi domain controller environment... please NEVER do a full VM restore. It will break your domain and you will run in USN rollback issues after some time. Application aware processing prevents that

Best regards,
Hannes

[wessel@RUC]

Hi HannesK !
Thank you very much for thorough reply and explaination, i understand VVS ..your explanation gives me a good understanding, and i reckon your suggested solution will work most excellently ! The old DCs have their own old domain, separate from our main (new) domain.
- However, i was looking at a quick and dirty solution, simply excluding these old 2003 servers in the backup job (there is an option to exclude VMs), until i get around to upgrading / migrating them to new Server. We should not have old unsupported servers in our environment anyways.
Thant would work too i guess ?

[HannesK]

sure, you can also just exclude them. no backup - no error message

[wessel@RUC]

Excellent ! I ended up excluding them, and made them a new Backup job just with the the 2 old DCs without application aware processing enabled,
Thanks again for your insight. Case solved and closed.

[Gostev]

I just wanted to stress that application-aware processing is required for domain controllers specifically. You will not be able to restore them from backups created without application-aware processing enabled due to a "USN rollback" issue (Google for this term if you want more information).

I know Hannes already said this above, but I personally glanced over this part when reading his response, so decided to re-iterate this point in the dedicated post.

For users who need to protect Windows Server 2003 VMs, we highly recommend staying with version 9.5, which will remain supported until 2022.