Does a HyperV parent back up VHDs attached to children? Critique our backup configuration.

We have a Windows Server '12 R2 box hosting a couple of HyperV virtual machines.  The server has an internal RAID1 for local image backups and a RAID1-equipped NAS attached via iSCSI for "offsite" image backups.  (I say offsite because the NAS is in another building, albeit one right next door.  There is also a files/data/databases-only truly-offsite backup service running on the HyperV children.)  

We are using Windows Server Backup on the HyperV parent to make nightly incremental backups of the host and children to the internal RAID1.  I've selected "custom" backup, with the following components specified.  The internal RAID1 (E: drive) and the iSCSI NAS (F: drive) are specifically excepted from the backup set, obviously.
--bare metal recovery
--system state
--child 1 (online)
--child 2 (online)
--EFI system partition
--System C: drive
--HyperV D: drive

On the NAS, we've created fixed-size VHDxes for the children.  Using HyperV manager, we've attached a VHDx to each child.  Then, in each child, we've configured Windows Server Backup to do nightly incremental backups to its VHDx.

We'd implemented the internal RAID1 backups a month ago when the server was deployed.  The child backups were just set up in the last couple of days.  This morning, I checked the HyperV parent's backup and it was still running.  It was working on Child2, and the status indicated that it was at about 250GB.  Child2 only has a 200GB partition, with about 80GB used, not including the VHDx where its backups are stored.  

My guess is that the HyperV parent is not only backing up Child2's 200GB OS partition but also its backup VHDx. (I had assumed that it wouldn't do that.)  Either that, or the schedules for the HyperV parent and Child2 overlapped, causing some sort of nonesense.  I'm running a HyperV parent backup right now to see what happens.

In the meantime, anyone who'd like to critique or comment on our backup scheme, please feel free to share.  (There's not really any points for that part, unless we're doing something egregiously wrong and your input saves us from impending disaster.)
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Toni UranjekConsultant/TrainerCommented:
You guessed right. Parent and child backups are overlapping. Maybe you can change backup schedules?

I will not critique your backup plan because it is better to have two backups than none. ;)

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SINC_dmackAuthor Commented:
I checked on the manual HyperV parent backup and when it got to Child2, it said that it was backing up 1.07TB.  Considering that Child2 has about 80GB used out of a 200GB partition, and considering that the backup VHDx is 1TB, it seems pretty obvious that the HyperV parent backup is grabbing the backup VHDx in addition to the OS partition even though the backup VHDx is stored on an iSCSI NAS.

If I change the HyperV parent backup to omit HyperV, it will still take snapshots of the child VHDs on the parent's D: drive, but it won't pull the backup VHDxes that the children are using.  But, is there any danger of data being missed during the backups if I omit HyperV from the backup set?

As a test, I'll restore one of the VHDs from tonight's backup and see if it will mount and run properly, but I'm interested in third-party input as well.
SINC_dmackAuthor Commented:
I have the HyperV parent set to back up itself and all of the children to local storage at 1AM, and each of the children set to backup to a NAS every hour after that--IE, child1 at 2AM, child2 at 3AM, etc.  All of the backups are working properly, taking up the correct amount of space, and do not appear to be overlapping, so everything is well.
SINC_dmackAuthor Commented:
Ensuring that the backups are not overlapping appears to have resolved the issue.
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