A quick look at storage
** This piece has been updated to reflect changes since first posting. See page two for PCIe RAID results! **
Our Intel Skylake launch coverage is intense! Make sure you hit up all the stories and videos that are interesting for you!
- The Intel Core i7-6700K Review - Skylake First for Enthusiasts (Video)
- Skylake vs. Sandy Bridge: Discrete GPU Showdown (Video)
- ASUS Z170-A Motherboard Preview
- Intel Skylake / Z170 Rapid Storage Technology Tested - PCIe and SATA RAID
When I saw the small amount of press information provided with the launch of Intel Skylake, I was both surprised and impressed. The new Z170 chipset was going to have an upgraded DMI link, nearly doubling throughput. DMI has, for a long time, been suspected as the reason Intel SATA controllers have pegged at ~1.8 GB/sec, which limits the effectiveness of a RAID with more than 3 SSDs. Improved DMI throughput could enable the possibility of a 6-SSD RAID-0 that exceeds 3GB/sec, which would compete with PCIe SSDs.
Speaking of PCIe SSDs, that’s the other big addition to Z170. Intel’s Rapid Storage Technology was going to be expanded to include PCIe (even NVMe) SSDs, with the caveat that they must be physically connected to PCIe lanes falling under the DMI-connected chipset. This is not as big of as issue as you might think, as Skylake does not have 28 or 40 PCIe lanes as seen with X99 solutions. Z170 motherboards only have to route 16 PCIe lanes from the CPU to either two (8x8) or three (8x4x4) PCIe slots, and the remaining slots must all hang off of the chipset. This includes the PCIe portion of M.2 and SATA Express devices.
Back in 2006, storage tech talk was intermittently buzzy with a few different innovations. One was wrapped around the pending release of Windows Vista, particularly two bullets on its feature list: ReadyBoost and ReadyDrive. In parallel with all of the Ready_____ talk, many tech pundits asked why it would be necessary to have the flash talk to Windows through special drivers. Why couldn't the flash memory just act like a larger RAM cache already present on?
A prototype ReadyBoost-enabled HDD by Samsung.
The answer, which nobody was aware of at that time, was that management of flash memory was a tricky thing to do successfully. It would not be until several years later that SSD's would (mostly) beat the issues of Long Term Performance and other issues that crop up when attempting to store randomly written data onto a device that can only be erased in relatively large blocks.
ReadyDrive required a special 'Hybrid' disk drive to be connected to and recognized by Windows Vista, containing both spinning platters and flash memory. Vista would then place frequently used small files on the flash. Since flash memory has negligible access times when compared to seek times of a HDD, the drive overall would boot significantly faster. Other tasks using those cached system files also saw a benefit. While ReadyDrive looked great on paper, there were very few devices ever released that could take advantage of it. Seagate was the earliest to release such a drive, and their Momentus 5400 PSD laptop drive did not see the light of day until Vista was nearly a full year old.