Quantifying Benefit and Cost of Erasure Code based File Systems

We perform a quantitative analysis of the costs and benefits of using file systems whose long term reliability methods are based on erasure codes. We compare it with replication a special case of erasure codes that is used in many reliable file systems. Our main goal in benefit analysis is to see how much of an increase in the expected system lifetime can be achieved with erasure codes or the storage requirement decreased given the same system lifetime requirement as a replicated system. Our main goal in cost analysis is to model the effect of erasure codes on latency and throughput of the system taking into factor code properties like decoding time and complexity. We also present a case study where we use previously measured values for the parameters of our modeled system to get an idea of the behavior of a real system.