On Mon, 06 Jul 2009 16:13:17 -0400 "Rosenbaum, Larry M." <rosenbau...@ornl.gov> wrote:
> Has anybody considered revising the Bayes expiration logic? Maybe > it's just our data that's weird, but the built-in expiration logic > doesn't seem to work very well for us. Here are my observations: > > There's no point in checking anything older than oldest_atime. For > this value and older, zero tokens will be expired. The current > estimation pass logic goes back 256 days, even if the oldest atime is > one week and the calculations have already started returning zeroes. > > If your target corresponds to a delta of more than a few days, you're > unlikely to get very close to it because the estimation pass logic > uses exponentially increasing intervals. There could be a big > difference between 8 days and 16 days for delta. This sounds pretty bad. What I would do is this: Compute the fraction of the tokens to be deleted. Sample a few thousand random tokens, and apply the same fraction to the samples. Take the atime of the oldest sample token that would survive, use that as the new max-atime, and delete anything older from the database.
