As part of our visit to Samsung in New York yesterday, the company shed some new light on Z-NAND, its high-performance, low-latency non-volatile storage product. Z-NAND is meant to compete with the 3D Xpoint memory that Intel uses to build its Optane SSDs and non-volatile DIMMs.
Samsung's 983 ZET Z-NAND SSD
According to Samsung, Z-NAND is the name for a single-level-cell implementation of the 3D V-NAND flash that underpins practically every one of its solid-state storage products. Companies have largely abandoned making SLC SSDs in favor of the density and lower costs per gigabyte of multi-level cell (or two-bit-per-cell), triple-level-cell, and even quad-level cell NAND SSDs, but certain customers still need the performance and endurance that a single bit per cell provides.
That demand is part of the reason Intel introduced 3D Xpoint memory and began offering Optane SSDs for the data center. Companies like Aerospike were still purchasing some of the last SLC SSDs available as caching drives for their in-memory database applications, but supplies for those drives ultimately began to dwindle and opened the door for alternative products to come to the fore. The growth of applications that need both high performance and space for large data sets apparently prompted Samsung to begin making SLC NAND for the data center again.
Beyond the implementation of SLC, Samsung said its engineers worked to lower the programming time of Z-NAND to help meet its latency goals for these SSDs. Z-NAND drives also use a large DRAM buffer—1.5 GB in the case of the 983 ZET—that further helps performance. The use of this buffer partially explains the balance between read and write performance that Samsung made for the 983 ZET, however. Read speeds aren't affected by the buffer, but write speeds are hampered by the fact that the drive has to commit whatever is in its DRAM to the underlying flash periodically. Stay tuned for more information on what we learned about Samsung's new data-center SSDs soon.