After forgetting to create the no_sms_on_drive.sms check files on my new ConfigMgr 2012 install (admit it, we’ve all done it) I just realised I had several GB of files sitting on a volume I didn’t want them on.
Luckily I found out about this tool to help save the day, included in the CM12 SP1 toolkit.
ContentLibraryTransfer.exe to the rescue
Annoying stuff I figured out (or am trying to) 
I am running into the same situation where there is about 20 gig of data in the library on my database server. Can this tool be run on site servers that are not DPs?
What library are you referring to? Is your database server separate to your primary or hosted on the same machine?
Let me try to re-word this. I’m trying to see if i can use the tool to move the SCCMContentLib folder on my Site Server. This is a non-DP system. Any thoughts? I know the documentation says: that the tool can be run locally on the DP.
I can’t recall if it said anything about being for DP only servers, but it worked fine for me on my Primary Site server which is what I assume you are also wanting to use it on. I also have my SQL database on the same server.
Usual caveats apply, backup first of course and if you have a lab environment, test it there first.
Thanks and yes, i plan on performing this step on the primary site server (db is on the same server). Thanks again!