Hybrid Storage Roundup: Seagate Momentus XT vs. OCZ RevoDrive Hybrid vs. Intel Z68
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.
A prototype of the Momentus 5400 PSD, seen near the Vista launch. This drive was available in up to 160GB, yet had only 256MB of flash memory.
ReadyBoost, on the other hand, allowed much of the same performance enhancements to take place without the use of a 'special' HDD. Users would simply supply their own USB flash drive and configure it as a ReadyBoost drive. Vista would do the same sort of thing it did with the Hybrid drive, but there were further advantages in that users were not limited to the few hybrid HDD's available, and could supply a USB drive of much greater capacity than the flash portions of then current Hybrids. The end result was the (relatively) few users of ReadyAnything favored the Boost variant, and thoughts of any form of 'true' Hybrid caching solution would not surface until early 2011 with the introduction of the Intel Z68 chipset, which allowed the pairing of a SSD and HDD to boost performance. This pairing took place at the storage driver level, meaning that much more than just Windows system files could be cached. In addition, the cache was connected via SATA (as opposed to ReadyBoost's USB link), resulting in even further gains.
Today we're going to take a look at the more recent hybrid solutions available. These use neither ReadyBoost nor ReadyDrive, and operate at the storage subsystem level. Some require special hardware and/or drivers, while other are plug and play. Here's the batch:
OCZ RevoDrive Hybrid, Intel Larson Creek, Seagate Momentus 7200.4 and XT G1 + G2 Hybrid drives.
Time for some testing!