I have a laptop with Haswell Core i5 and Intel Rapid Storage Technology.
The OS drive is an mSATA Samsung EVO 840. As you may have heard, they had some miscalibration leading to excessive retries and very slow transfer speeds, as data on the drive ages. There's a tool from Samsung for rewriting the data to make it "young" again, and a firmware update that may or may not prevent the problem from recurring.
The drive is configured with Intel Rapid Start and Smart Response Technology (30GB as cache for the 2.5" rotating SATA drive, 220GB for OS), and this uses the "RAID" mode and Intel driver. The Samsung tool cannot communicate with the drive, blaming the Intel drivers. Evidently they don't pass vendor SATA commands through to the drive.
Is there a way to perform the firmware update / data refresh without losing the caching feature? I'm willing to disable acceleration temporarily in order to accomplish this, but AFAIK if I revert the drive to "available" I cannot re-enable caching without wiping the disk and reinstalling the OS. Does someone know otherwise? Is there a workaround? Put the drive in a eSATA dock during update or something like that?