Azure Backup Server (DPM) fails with "There is insufficient free space in the storage pool for this protection group. To increase the free space, cancel this wizard and add disks to the storage pool or remove non-DPM volumes from the disks in the storage pool. To assign custom volumes to selected members, click Modify."

When you try to create a new Protection Group you are faced with the following problem "There is insufficient free space in the storage pool for this protection group. To increase the free space, cancel this wizard and add disks to the storage pool or remove non-DPM volumes from the disks in the storage pool. To assign custom volumes to selected members, click Modify."

This was because the Storage Pool disk that had been configured had a partition on it. The disk must be in the raw format in order to create a new Protection Group. 

After deleting the partition from inside Disk Management, the Protection Group wizard allowed me to continue. 

Azure Backup error 2145124329 incompatible with SBS 2011 & Exchange Server 2010

When installing Azure Backup on to SBS 2011, the installation fails with Error 2145124329, and does not complete. It appears Windows Management Framework 3.0 is required for the Azure Backup agent to install correctly, however Exchange 2010 does not support WMF 3.0.

This article goes into better depth on what issues WMF 3.0 causes on SBS/Exchange;

https://blogs.technet.microsoft.com/sbs/2012/12/15/windows-management-framework-3-0-applicability-on-windows-small-business-server-20082011-standard/

Luckily I have just completed migrating all the e-mail from Exchange 2010 to Exchange Online, therefore I uninstalled Exchange. Once this was uninstalled, I then manually installed the WMF 3.0 and the Azure Backup Agent install completed successfully. 

Interestingly enough WMF 3.0 did break the SBS Console (but who cares because it's horrible anyway)! Moral of the story is, if you are using SBS 2011 and can't rip Exchange off the box you can't use Azure Backup.