PCI Express-Attached M.2: Ready For Prime Time
SanDisk's A110 is the first SSD in our lab based on the M.2 form factor. It's an intriguing piece of technology. Alleviating SATA's 6 Gb/s bottleneck allows the native PCIe controller to achieve impressive sequential performance, though random throughput is biased toward low queue depth environments. That's alright by us, though. In the mobile devices designed to accommodate SSDs like the A110, this level of performance is still downright phenomenal.
M.2 is picking up steam, and alongside it, storage vendors are starting to talk about a feature called DevSleep, which facilitates ultra-low idle power consumption at the expense of some extra latency as you resume. But this is a part of the SATA specification; you can't get it from a PCI Express-based drive with an M.2 connector. So naturally, the A110 doesn't support DevSleep.
We're sure that PCI Express-based SSDs, and then PCI Express-based SSDs with NVMe support are going to receive the most attention from enthusiasts. However, those SATA-based models will likely ship in the highest volumes.
On the desktop, power users can get as much storage performance as they want by slapping SSDs together in RAID. But that's simply not an option in most mobile devices. So, in some situations, SATA will be deemed plenty sufficient. In others, solutions like the A110 will enable more performance in less space. What's cool is that drives for both applications can be built using a number of form factors and the M.2 connector.
SanDisk's A110 represents growing number of options in the storage world, and we like that. Particularly now, as one high-performance SSD after another slams into the same SATA-imposed ceiling, it's exciting for a storage enthusiast like myself to get an early look at the edge connector and controller hardware that'll help change the status quo, knowing all along that there's an interface (NVMe) coming as well that'll complete the picture and further unlock the potential of solid-state storage.
Until that happens, though, we have SATA- and PCIe-based SSDs with M.2 connectors and AHCI compatibility already in production. It's only a matter of time before Haswell-based Ultrabooks start showing up in greater numbers with their own little M.2 slots. And it's good to know they'll be nice and fast, isn't it?