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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?

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I have the same issue on an x366 w/ ServeRaid 6 and two drives (WD I think, not sure). They were previously physically limited (jumper) on another system, but even without the jumper, it doesn't work faster... – petrus Jul 12 '10 at 22:56
same here. Even IBM can't (doesn't want) answer. It could even be that we see 1.5 but it works at 3.0. It's hard to say because they are in raid and I can't compare the speed with any other similar hardware – damko Jul 25 '10 at 15:56
up vote 1 down vote accepted

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.

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.

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thank you very much for pointing me to that page. I'm not sure if the backplane is the same but I was pretty sure that there was something wrong. You are right, this sucks and I'm tired to deal with several thousands dollars servers with any kind of hardware issue: and this happens with HP and IBM ... it seems that is considered "normal" by any brand ... China effect? – damko Jul 30 '10 at 9:50

Tell me about it. It's almost more cost effective to just build a server with off the shelf products. I'm going to look into an external enclosure to see if I can run SAS drives on the server and SATAII SSD's on an external enclosure.

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if you are looking for an external enclosure I suggest products like this… attached to a ServeRaid with multilane ports. Careful: often ServeRaid don't support disks bigger than 1TB – damko Aug 2 '10 at 7:44

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