We present WiscKey, a persistent LSM-tree-based key-value store with a performance-oriented data layout that separates keys from values to minimize I/O amplification. The design of WiscKey is highly SSD optimized, leveraging both the sequential and random performance characteristics of the device. We demonstrate the advantages of WiscKey with both microbenchmarks and YCSB workloads. Microbenchmark results show that WiscKey is 2.5×–111× faster than LevelDB for loading a database and 1.6×–14× faster for random lookups. WiscKey is faster than both LevelDB and RocksDB in all six YCSB workloads.