How to prevent having a data grave?

[Andreas J. Koenig]

Since I set up our first mogilefs cluster, we start worrying about how
to cleanup the data we do not need anymore.

Can other users share their stories about how they cope with this
problem? One demand is that we should be able to store user-defined
data along with every file. I think my answer is, you can do that by
appending something like ".meta" to the key and store it in some
cleanup class.

In our first project the only interesting meta data would be access
time. How do people track access time? By storing it or by going
through the mysql database and see the accesstime on the real storage
device?

Any tips and stories welcome,
Thanks,
-- 
andreas