I'm looking for a tool to maintain the integrity of a filesystem and it's contents using checksums. Effectively storing a list of checksums/filename pairs somewhere on the filesystem in a way that can be verified later if files are somehow damaged or lost.

Git does what I want, but because it stores the contents of every file in it's object database, the disk usage will at least double. And the fact that it does not provide a progress bar when scanning files tells me it was not designed for the multi-terabyte filesystem I have in mind.

I can do this crudely by storing the output of md5deep, but is there a tool specifically designed for this purpose, using whatever smarts possible to make the process efficient?