The old SATA interface may be much slower than PCIe but it is still useful in many use cases.
Micron Technology is bucking the trend of moving to PCI Express-based storage and releasing a new SATA III-based SSD with ultradense memory storage and read optimized for faster data access.
The SATA interface has been around since the beginning of the century, but it has progressed much slower than the PCIe interface and with nowhere near the leaps in performance. Among gamers, who are as obsessed with performance as someone doing AI models, PCIe drives are standard issue, and SATA drives are at best used for storage.
That’s because SATA III has a throughput of about 550MB/s, while PCIe 4.0 has more than 10 times the throughput.
SATA III is more than enough in modest use cases. For example, 50 gigabit Ethernet consisting of two 25Gb/s ports can easily be filled with data by 12 SATA drives. That is about half the number of drives that fit in a 2U storage array when using the standard 2.5-inch drive form factor, says Alvaro Toledo, vice president and general manager of data center storage at Micron.
So for basic functions like file storage and line-of-business applications, SATA does the job just fine. For HPC and AI modeling, you would use a PCIe-based storage array. “It’s all about the right tool for the job,” said Toledo. “I’m not going to tell you that high performance AI-type workloads are using SATA.”
To that end, Micron is introducing a 176-layer TLC NAND SATA SSD, the Micron 5400 line. TLC means the memory cells in the NAND flash chips hold three bits each. There is a higher density NAND flash, QLC, with four bits per cell but it has a much lower durability rating than TLC.
The 176-layer memory is quite a leap. For some time, NAND memory has engaged in 3-D stacking to increase density in a small space, and the highest density has been 128 layers. Adding 48 more layers means more density per chip, and thus greater storage. The Micron 5400 line scales from 240GB to 7.68TB.
Toledo says the 240GB drive is primarily used for boot images and holds just the operating system while the higher capacity drives are used more for storage and large numbers of reads and writes. The 7.68TB drive is especially tuned for high-performance reads, because the assumption is that customers use it for mass storage, said Toledo.
Micron said OEM partners are in the middle of qualifying the memory for their drives, with some shipping to the channel now.