KVRAID: high performance, write efficient, update friendly erasure coding scheme for KV-SSDs

Key-value (KV) stores have been widely deployed in a variety of scale-out enterprise applications such as online retail, big data analytics, social networks, etc. Key-Value SSDs (KVSSDs) provide a key-value interface directly from the device aiming at lowering software overhead and reducing I/O amplification for such applications.

In this paper, we present KVRAID, a high performance, write efficient erasure coding management scheme on emerging key-value SSDs. The core innovation of KVRAID is to use logical to physical key conversion to efficiently pack similar size KV objects and dynamically manage the membership of erasure coding groups. Such design enables packing multiple user objects to a single physical object to reduce the object amplification compared to prior works. By applying out-of-place update technique, KVRAID can significantly reduce the I/O amplification compared to the state-of-art designs. Our experiments show that KVRAID outperforms state-of-art software KV-store with block RAID by 28x in terms of insert throughput and reduces CPU utilization, tail latency and write amplification significantly. Compared to state-of-art KV devices erasure coding management, KVRAID reduces object amplification by ~ 2.6x compared to StripeFinder and reduces I/O amplification by ~ 9.6x when compared to KVMD and StripeFinder for update intensive workloads.