GlobLease: A globally consistent and elastic storage system using leases

Nowadays, more and more IT companies are expanding their businesses and services to a global scale, serving users in several countries. Globally distributed storage systems are employed to reduce data access latency for clients all over the world. We present GlobLease, an elastic, globally-distributed and consistent key-value store. It is organised as multiple distributed hash tables (DHTs) storing replicated data and namespace. Across DHTs, data lookups and accesses are processed with respect to the locality of DHT deployments. We explore the use of leases in GlobLease to maintain data consistency across DHTs. The leases enable GlobLease to provide fast and consistent read access in a global scale with reduced global communications. The write accesses are optimized by migrating the master copy to the locations, where most of the writes take place. The elasticity of GlobLease is provided in a fine-grained manner in order to precisely and efficiently handle spiky and skewed read workloads. In our evaluation, GlobLease has demonstrated its optimized global performance, in comparison with Cassandra, with read and write latency less than 10 ms in most of the cases. Furthermore, our evaluation shows that GlobLease is able to bring down the request latency under an instant 4.5 times workload increase with skewed key distribution (a zipfian distribution with an exponent factor of 4) in less than 20 seconds.