The scheduled wbadmin backup to \\server\rd1000 stopped working, so I looked into things a bit more and have now changed my servers to backup to the drive directly. wbadmin behaves as if it’s backing up to a DVD or something, and we have to pipe some input into it.

It goes something like this:
Make a file called c:\unattend.txt, which contains:

C
Y

(C on one line, and Y on another). This will be piped into the wbadmin command’s input, because wbadmin prompts us to “press C to continue”, and “press Y if you’re sure”.

Then the backup command looks like this:

wbadmin start backup -backuptarget:d: -allcritical -quiet <c:\unattend.txt >>”C:\Company Shared Folder\BackupLog.txt”

The -quiet is important because we are relying on very specific behavior/prompts, to which our unattend.txt file responds. i.e. without the -quiet, we’ll not get the “C” and “Y” prompts and so our unattend.txt will provide unsuitable input.

In the above case, the RDX drive is D:

The output is appended to C:\Company Shared Folder\BackupLog.txt