Firmware as the performance differentiator for SSD controllers

By _Cadence - Denali Memory Report

April 19, 2010

Anandtech has just posted a meaty article about SandForce SSD controllers as used in SSDs from OCZ and Corsair. (Understanding SandForce's SF-1200 & SF-1500, Not All Drives are Equal) It’s worth a read from at least two perspectives. First, it gives you some pretty deep insight into the real importance and value of the firmware running on these SSD controllers. As the Anandtech article discusses, controller firmware can make a substantial performance difference using the same hardware. In the case of the SandForce SF-1500 enterprise SSD controller and the company’s SF-1200 “client” SSD controller chips, firmware makes all the difference in performance because the two devices are electrically the same IC. Both chips running their associated firmware are rated at 30K random-read IOPS (I/O operations per second for 4-Kbyte reads) but the SF1500 is rated at 30K random-write IOPS (4-Kbyte writes) while the SF-1200 is rated at 10K random-write IOPS, which is a whopping two-thirds less performance than delivered by the electrically identical SF-1500 controller chip. There’s also an order-of-magnitude difference in rated data reliability between the two controllers, which you’d expect customers to want for enterprise-class SSDs. From the perspective of product positioning, this performance spread makes tremendous sense because the enterprise-class SF-1500 is reported to be substantially more expensive than the SF-1200 and the price premium is largely attributable to the differential speed and data-reliability performance delivered by the controller firmware (along with some extra reliability testing for the SF-1500 chip).