LightStore: Software-defined Network-attached Key-value Drives.

We propose LightStore, a key-value flash store, as a substitute for x86-based storage servers. A LightStore node has a low-power embedded-class processor, a few gigabytes of DRAM and a few terabytes of NAND flash, and can be directly connected to a network port in a datacenter. A large-scale distributed storage cluster can be formed simply by adding more LightStore nodes to the network. Applications in a datacenter can take multiple software-defined views of LightStore stores via thin LightStore adapter layers, which translate conventional KV, YCSB, block, and file accesses to KV ones for LightStore. LightStore is estimated to be 2.0x power-efficient and 2.3x space-efficient than an x86-based all-flash array system of the same capacity. Experimental results on our LightStore prototype show that 1) the LightStore node performance is comparable to an x86 server with a single SSD; 2) a four-node LightStore cluster exhibits up to 7.4x better ops/J than an x86 server with four SSDs.