The Serial ATA International Organization (SATA-IO) has ratified the SATA 3.2 storage spec, adding support for a SATA Express spec that can piggyback on faster PCI Express lanes, and defining a new embedded single-chip microSSD. SATA 3.2 also embraces the tiny, SATA Express based M.2 form factor, which debuted in recent Intel and Samsung SSDs.
Just as PATA (parallel ATA) was replaced by SATA storage that used a faster serial interface, SATA is now evolving to speed down the faster PCI Express lane. SATA 3.2’s primary enhancement was enabled by the ratification of the SATA Express spec in January. SATA Express allows SATA and PCI Express (PCIe) storage solutions to coexist, enabling a compliant host to support both. The key benefit is that SATA drives can now use the faster PCIe interface. This is especially important as increasingly speedy solid state drives (SSDs) have become faster than SATA.
Tiny Samsung PCIe SSD beside a 100 Won coin
When using dual PCIe 3.0 lanes, SATA 3.2 SSDs can operate at speeds of up to 2GB/s, compared to 0.6GB/s (6Gb/s) for SATA 3.0. The use of PCIe is optional, and traditional hard disk drives (HDDs) and optical drives using serial interfaces will continue to be supported.
Mobile device developers will likely use PCIe connections in conjunction with SATA 3.2’s new M.2 form factor (shown below), enabling thin, 80 x 22mm M.2 SATA SSDs suitable for tablets and thin notebooks. Initially defined by PCI-SIG as NGFF (next-generation form factor), M.2 supports technologies like WiFi, USB, PCIe, and SATA. Intel and Samsung have already announced M.2 form-factor drives, although only Samsung’s uses SATA Express (see farther below).
M.2 SSD form-factor specs from Intel’s SSD Drive 530 Series
(click images to enlarge)
The SATA 3.2 spec further defines a microSSD standard for even smaller, single-chip SATA implementations for embedded storage. MicroSSD eliminates the module connector from the SATA Interface, enabling SATA to use a single ball grid array (BGA) package. The device can solder directly onto a motherboard via a new electrical pin-out. The Sandisk iSSD is shown at the right (click image to enlarge).
Other new features in SATA 3.2 include:
- Universal Storage Module — USM enables removable and expandable storage for consumer electronic devices. Specifically, SATA 3.2 debuts a new USM Slim format, which as the name implies, reduces module thickness.
- DevSleep — This new ultra-low power management state brings the drive to a point where it is “almost completely shut down,” according to SATA-IO.
- Transitional Energy Reporting — SATA 3.2 now provides the host with more detailed power management reporting.
- Hybrid Information — The host can now send data caching information to the drive, improving solid state hybrid drive (SSHD) performance.
- Rebuild Assist — This enhancement speeds data reconstruction in RAID configurations.
Samsung and Intel launch M.2 SSDs
Samsung’s M.2 form-factor XP941, which went into mass production in June, was billed as the first PCIe-based SSD. The XP941 family includes 512GB, 256GB, and 128GB SSD, and have already started shipping to manufacturers of ultra-thin notebooks.
Samsung’s XP941 PCI Express SSD compared to a Korean penny
The 80 x 20mm device is designed for 10-nanometer class NAND technology, which falls between 10nm and 20nm processes. The XP941 enables sequential read performance of 1,400MB/s, the top speed offered by a PCIe 2.0 interface. As a result, it can read 500GB of data or 100 5GB HD movies in only six minutes, claims Samsung. This is claimed to be seven times faster than an HDD and more than 2.5 times faster than the fastest SATA SSD.
The XP941 weighs six grams, compared to 54 grams for a typical 2.5 inch SATA SSD, and has “about a seventh” of the volume, says Samsung. The size and weight reductions enable greater power efficiency and ergonomics, and enable manufacturers to increase the size of the battery, providing even longer battery life.
Intel’s SSD 530 is a bit farther behind. The M.2-compliant Intel SSD 530 was announced in late July along with similar 530-branded models that use 2.5-inch SATA and mSATA form-factors. Unlike the Samsung XP941, however, it does not support PCIe, but is limited to SATA 6Gb/s and 3Gb/s connections.
Designed for 20nm MLC NAND chips, the SSD 530 is available in 360GB, 180GB, and 80GB capacities. The 80mm device weighs less than 10 grams, and operates on 140mW active, and 55mW idle, says Intel. By comparison the 2.5-inch 530 model is said to operate at 190mW active. Performance is the same, however, with sequential reads and writes up to 540MB/s and 490MB/s, respectively.
More information on SATA 3.2 may be found at SATA-IO’s SATA 3.2 web-page. More on the new M.2 SSDs may be found at the Samsung XP941 announcement page and Intel 530 M.2 SSD product page, respectively.