I have a X3400 with 8 x (43w7598 250GB SATA 3GB/S HDD) set in the frontal bay and connected to ServeRaid 8K controller.
The raid array works well but, even if I set the controller PHY to 3.0 (rather then Auto or 1.5), all the disks negotiate 1.5Gb/s with the controller.
This sounds really weird to me because the disk are WD Caviar Black Sata2 disks (bought from IBM).
The firmware is the latest available from IBM (accordingly to the IBM ServeRaid matrix). Any tip?
Best Answer
The reason your Sata drives are running at 1.5Gb/s vs 3.0Gb/s on your server is because their was a bug in the backplane that caused 30 second freezes under heavy workloads. I have an X3650 which I believe has the same backplane as yours. I'm also running Serveraid 8k.
They found out that the SAS expander that bridges to the Sata devices had a limitation that prevented it from operating at 3.0Gb speeds on SATA II devices. Here is the actual link to the article.
http://www-947.ibm.com/systems/support/supportsite.wss/docdisplay?lndocid=MIGR-5071075&brandind=5000008
It really sucks because I spent a lot of money loading up the server with a couple of X25-E SSD drives, only to find out that they're stuck running at SATA1 which not only limits the performance, but cripples IO bandwidth on the HDD itself.