Caches in Content-Centric Networks (CCN) are increasingly adopting flash memory based storage owing to its efficiency. The current flash cache technology stores all files with the largest possible "expiry date," i.e., the files are written in the memory so that they are retained for as long as possible. This, however, does not suit the CCN data characteristics where contents are typically short-lived and have a distinct popularity profile. Writing files in cache using the longest retention time damages the flash memory thus reducing the flash lifetime. However, writing using a small retention time can increase the content retrieval delay, since, at the time a file is requested, the file may already have been expired from the memory. This motivates us to propose a joint optimization wherein we obtain optimal policies for jointly minimizing the content retrieval delay (which is a network-centric objective) and the flash damage (which is a device centric objective). Caching decisions now not only involve what to cache and where to cache but also for how long is each file cached. The optimality of our policies are shown analytically, and are compared against prior policies using simulations.
['Samta Shukla', 'Alhussein A. Abouzeid']
On designing optimal memory damage aware caching policies for content-centric networks