[Linux-PowerEdge] Negotiated Speed is different than Capable Speed

Zurd zurd33 at gmail.com
Thu Jul 24 20:14:20 CDT 2014

Hi, I have 3 servers and they all exhibit the same problem.

On the OMSA webpage in
System / Storage / SAS / Connector / Physical Disks and click on Full View
I see the Negotiated Speed at 1.50 Gbps and the Capable Speed at 3.00 Gbps.
It should show 3.00 Gbps not 1.50 Gbps.

The motherboard, the hard drive, the PCI Express card, they all support 3
Gbps but it's not showing it.

First server is a Windows PowerEdge 840 with a SAS 5/iR Adapter card with 4
HDs. The first 2 HDs are WD2500YS-18SHB1 and they show 3.00 Gbps for both
the negotiated speed and capable speed. Those 2 HDs came from Dell itself.
But the 2 others HD, not from Dell, in this server are WD1002FAEX-00Z3A0
and they show 1.50 Gbps. All of those HDs are using the same cable plugged
in the same PCI Express card.

Another is a Linux OptiPlex 745 with a SAS 5/iR Adapter with 2 HDs in it.
Both show 1.50 Gbps of Negotiated Speed. Runs at around 30-40 MB/s when
tested with hdparm and dd.

The 3rd server is Linux and also has the same problem, I don't have the
specs right now but I could find it if needed and the HDs are not from Dell

I'm then wondering if maybe only HDs from Dell can go up to 3 Gbps. Or is
there a setting needed to be done on other HDs? Anyone can also confirm
that this is a bug? What do you see in the Negotiated and Capable Speed?
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