Hi, I have a new build of DPM 2012 R2 rollup 7 running. It's mostly running well, however over the weekend my backups to Azure failed, due to my C drive filling up from the cache. I am wondering, is there any way for me to relocate this cache location to a new place without re-installing the MARS agent? 

Hi,

https://azure.microsoft.com/en-us/documentation/articles/backup-azure-backup-faq/

Q1. How can I change the cache location specified for the Azure Backup agent?

Stop the OBEngine by executing the below command in an elevated command prompt:

PS C:\> Net stop obengine

Copy the cache space folder to a different drive with sufficient space. We recommend you copy the files from the cache space folder instead of moving them; the original cache space can be removed after confirming that the backups are working with the new cache space.

Update following 2 registry entries with the path to new cache space folder:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows Azure Backup\Config
ScratchLocation - New cache folder location

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows Azure Backup\Config\CloudBackupProvider
ScratchLocation - New cache folder location

Start the OBEngine by executing the below command in an elevated command prompt:

PS C:\> Net start obengine

Once the backups happen successfully with the new cache location, you can remove the original cache folder.