Date: Tuesday , April 30, 2013
We recently published a product evaluation of the ADATA XPG SX900 128GB SSD that uncovered some issues with the drive. The ADATA XPG SX900 SSD isn't new, it has been on the market for well over a year. The interesting aspect of the hardware we received was the unexpected emergence of the new SF-2281VB2 controller.
The new VB2 stepping of the SandForce controller is merely the continuing evolution of the SF-2281 controller. SandForce representatives have mentioned this new stepping in the past, but no specific timeline was given for the release. Having it pop up in the wild with no announcements was surprising. The VB2 version of the venerable SF-2281 provides revolutionary advances in power consumption through a host of techniques, including shutting off several NAND packages during low use periods and enhanced device sleep states.
We initially tested the ADATA SX900 and came away wanting. Wanting new firmware to be more specific. We suspected the problem we encountered was a byproduct of the old firmware that ADATA was using with the SX900. Not only was the firmware old, it was three generations behind the current version we are seeing in mainstream use.
During initial testing of the SX900 we noticed some unusual power consumption figures, above any SSD we have tested. One of the variables we routinely monitor, the startup voltage of the SSD, was exceedingly high. We were noting peaks of up to 10.9 Watts during this period, and then a 10-second interval of 7 Watts, followed by a reduction into the idle wattage. The highest values we have observed in the past were in the 4-Watt range, so understandably this piqued our interest.
After some research we were informed that the power saving features of the SF-2281VB2 controller are a combination of firmware and hardware optimizations, and without the correct version of firmware the power saving features aren't triggered into action. This information understandably pointed the finger for the errant power consumption in the direction of the older firmware revision.
After updating the previous sample with the new firmware, we found that the errant power consumption figures could not be tied to the incorrect firmware. The issue persists with the original sample, even with the new firmware. There is the chance this is the result of malfunctioning power components onboard the SSD. In an attempt to rectify the issue with the original sample, we conducted a closer inspection of the firmware revision used with the SX900.
We found that not only was ADATA late with its firmware, but it was also using a firmware that had broken TRIM when newer versions were available. Adding to the story, ADATA's customers had been asking for newer firmware revisions to fix the loss of TRIM. This led us to find that the SSD sample ADATA provided for our testing was using an older firmware (5.0.2a) that was not compatible with the new power saving VB2 features.
Unfortunately our initial review of the ADATA SX900 ended with us questioning ADATAs support, and the lack of a coherent firmware release timeline. This prompted a flurry of communication with ADATA, and we were informed that there had been 'issues' porting over previous firmware revisions to the varying builds the SX900 had undergone during the life of the product. There were significant changes to the BOM of the original SSD and rebranded NAND that made it impossible to discern the type or stepping. Switching the Build Of Materials (BOM) as new techniques and components become available is common with SSDs, but usually more radical departures from the original SSD call for a new SKU or modification of the published specifications.
ADATA provided us with a new sample with the latest LSI SandForce 7.0.3a firmware revision. The new sample has yet another BOM with 16 IMFT NAND packages. We inquired about the new BOM, and were assured by ADATA that it will be shipping this version in the future and that there will be no rebranded NAND on future products.
The ubiquitous SF-2281 is by far the most widely deployed controller in the SSD market, but it is also one of the oldest controllers still in widespread use. The new enhancements in power consumption make for great SSDs for mobile applications, and as we hold our breath for the new LSI SandForce controller to drop, we test the working VB2 stepping against other SSDs on the market.