Okay today I believe have learned some important lessons about SAS3 drives. I purchased 13 HGST 4TB SAS3 drives, I have a 9361-8i 1G cache and a 9361-8i 2G cache. I am using Startech HSB4SATSASBA enclosures. Now here is some of the fun that is to be had... The 9361s detect the fact that these are SAS3 drives - cool I thought I was only expecting SAS2 but if I get a nibble of extra speed out of it then hey I'm happy. This is where the fun begins and first I'll say what to do and then why. Do NOT let your controller set the drive interface speeds as AUTO - set them to SAS2 : if you don't you may encounter the following issues: 1) Performing a chkdsk /f /r on a JBOD drives results in bad sectors being reported. 2) Performing the same chkdsk operation on the same drive shows - no bad sectors... WTF???? (2 Wastes 5 hours per check ) 3) Random inexplicable sense errors when copying data to the drives.. OH Crud. 4) Drive for some reason seemed to completely vanish from the array - luckily it was only the hotswap spare. Although I am going to physically check the connector on the inside of the enclosure tomorrow to confirm my suspicions I suspect that there is a physical difference between SAS2 and SAS3 connectors in the respect that there number of pins on the connector is larger for SAS3, I have a certified SAS3 cable and although I have to look at the connector in the HSB4SATAASBA I suspect that in the gappy piece between what you would call normal looking headers that there are 8 small pins which supply an extra data lane back to the controller per drive and this is the reason that all of the above happened.. Yet again this is to be confirmed but I will update this tomorrow once I have checked. Since I set the physical interface on all drives to SAS2 - all the problems being reported in the logs - they are simply not happening now... Here is hoping it stays that way.