I have an MD3220 (6x2TB SSD Drives RAID6) and an MD1220 (20x900GB 10K SAS drives RAID6). I am direct attached from the ESX servers to the SAN via 6Gb and then the 1220 is attached via 6Gb, to both controllers, to the back of the MD3220. I am having the worst latency with the SAS tier. I mean, there is one VM on the SAS array and the latency is as high as 100ms. I just don't get it. I have no errors and other than it being painfully slow, everything appears to be in order. The latency on the SSD tier is around .0022. Crazy low! I would love any input on this. I've done this config once in the past and I never had this kind of issue. And this is back when I had 7200RPM drives in the 1220. help!
How many Host are physically connected to your MD3220? How many connections to each controller does each host have? Which Multipath policy are you using? For SAS MD3220 you want to use Round Robin. What is the current version of firmware on your MD3220 & your MD1220?
Please let us know if you have any other questions.