Popularity-based full replica caching for erasure-coded distributed storage systems

In most storage systems, the storage nodes store data on a local filesystem. Thus, unless they have a dedicated caching layer, they benefit from the usual filesystem cache in the host’s free memory. However, in erasure-coded storage systems, caching is effective only if all the systematic fragments corresponding to an object are in the cache. In this work, we propose a new caching policy adapting traditional methods to erasure-coded storage systems. The main idea of our solution is to cache a full object rather than fragments object. A simulation-based evaluation showed that our full replica solution is able to improve the cache hit ratio and reduce the cache waste ratio compared to the traditional caching method. Moreover, experimental evaluation has been conducted. It indicates that our implementation not only validates the previous results but also shows that cache hits on full replicas have a better request response time.