this is why you should store everything in a flat file database, no licenses to worry about. It's the only sane thing to do. chmod them to 777 and put them in a public dir also.
One thing to remember when you do your own caching layer that can store days of content is: Don't update the last read tag on every single read as if it's a busy object it will swamp the hell out of storage just writing update times. Only update it if the last read marker is more than a day old.
Similarly on cleanup, don't bother ordering all the objects by their last used time, just lump them into 1 day or 1 hour buckets and do the math to see how many you need to keep. In my case we didn't have a fixed duration cache just the amount of high speed storage we wanted to use for 'fresh' data.