Cost analysis of erasure coding for exa-scale storage

With the increasing demand for mass storage, research on exa-scale storage is actively underway. When the scale of storage grows to the exa-scale, the space efficiency becomes very important. To maintain the storage reliability and improve the space efficiency, we have begun to introduce erasure coding instead of replication. However, erasure coding has many I/O performance degradation factors such as Parity Calculation, degraded I/O, Data Distribution cost, etc., whereas the existing research mainly focuses on improving the performance of the Parity Calculation.In this study, we identified the issues and bottlenecks of using erasure coding in real storage. First, we measured the I/O performance of various erasure codes to find the suitable erasure codes for real storage. Next, we analyzed the execution time for each processing step when I/O was performed and the issues when erasure coding was used in storage. Finally, we predicted the cost of EC-based I/O processing in the exa-scale storage and identified the expected problems.