More information about the unconventional SSD used in Apple’s new MacBook Air. As I discussed in my previous coverage of this new flash form factor, it resembles a PCI Express Mini Card but is much smaller. Toshiba has now proved my speculation that the device uses SATA signals rather than the PCI Express lane used by the similar AirPort card. We also know that the lauded performance of the device is due to its chips and controller rather than skipping SATA in favor of PCIe as some had speculated.
Toshiba Blade X-galeâ„¢ HG Series SSD
Toshiba is one of the world’s largest NAND flash manufacturers, and the company uses these chips to produce integrated solid state disks (SSDs) for OEMs. Toshiba’s SSD product offerings are divided into two lines: The mainstream SG series and the high-performance HG Series. The SG line includes standard SATA, slim SATA, and mSATA cards, the latter using the Mini-PCIe form factor. These products only promise 50 MB/s of write performance, while the HG Series can top 180 MB/s writing.
Since the MacBook Air’s SSD is part of the third-generation HG series, its performance is much better than the SSDs used in typical netbook-class computers. NAND flash drives typically suffer during writes, but Toshiba promises sequential write performance for the HG Series of 180 MB/s, matching the read performance of their SG Series. This is almost as fast as the 3 Gbps SATA interface used!
Tiny SSDs like these can only use a few high-density flash chips, so eking out this kind of performance is doubly impressive. The “blade” form factor is about the size of a large USB flash drive and includes just four NAND chips on the top of the board. Toshiba includes both read and write cache in their controller, as well as encryption hardware which is apparently disabled by default. The device supports TRIM, even though Mac OS X does not (yet).
Toshiba offers Blade X-gale SSDs in 64 GB, 128 GB, and 256 GB models. Apple apparently uses all three, offering the smaller pair in the 11 inch MacBook Air and the larger two in the 13 inch model. These products are not available at retail yet, and Japanese reseller PhotoFast has apparently withdrawn their GM2 SFV1 Air Upgrade Kit which used similar modules, so there’s no telling when MacBook Air owners will be able to upgrade.
The 256 GB module is 3.7 mm thick, 1.5 mm more than the 64 and 128 GB siblings. One assumes that this reflects its use of 8 NAND chips rather than 4, and this might lead to better performance as well. Speaking of dimensions, the card is actually 24 mm wide and 108.9 mm long. My previous guesses were quite a bit off.
Stephen’s Stance
This new SSD form factor is certainly intriguing. Although no standard name has been coined at this point (Toshiba’s name, “Blade X-gale,” is a trademark), we will be watching with great interest to see if it catches on. I’ll be calling it a “blade SSD” until I hear a better name.
The compact dimensions of the connector and module itself should be welcomed by tablet and portable device manufacturers, and the fact that it can carry PCI Express as well as SATA signals makes it very appealing. The next-generation NAND chips should easily double capacity within the next year, too!