Flush Old Events from Eventstreams

[gmcquillan]

This is a bit of a controversial proposal, however at some point we need to figure out how to move old events out of redis-server, which requires that the data fit into memory.

We can go two routes with this:

1. Just remove items older than X, or items older than the latest Y items.
2. Use those same rules, but instead of deleting them, we serialize to disk.

I'm strongly leaning toward the second procedure, but I'm looking for comments.

Right now, Firetower at UA is taking up about 4G of memory, and generating about as much in logfiles everyday.