Understanding HBA speed on the internal PCI bus. (Doc ID 1526084.1)

Last updated on FEBRUARY 18, 2013

Applies to:

Solaris SPARC Operating System - Version 10 3/05 and later
QlogicFC HBA - Version All Versions to All Versions [Release All Releases]
Emulex FC HBA - Version All Versions to All Versions [Release All Releases]
Information in this document applies to any platform.
The customer installed a QLE8142 FCOE/CNA hba in his server.
He ran a qlogic utility to check the speed of the card on the internal PCIE bus in the server.

The utility gave him the following output:

PCIe Max Bus Width : x8
PCIe Max Bus Speed : 5.0 Gbps <-----------max speed of the card on a PCIE generation 2 bus
PCIe Negotiated Width : x4
PCIe Negotiated Speed : 2.5 Gbps <---------negotiated speed of the card when connected to a PCIE generation 1 bus
HBA Status : Online


The customer was concerned with the negotiated speed not matching the max speed in the output above.
The speed in the above output is referring to the internal bus on the server.
The hba is a PCIE generation 2 HBA. The internal bus PCIE bus on the server is PCIE generation 1.

The max speed on a PCIE generation 1 bus id 2.5Gbps.
The hba is PCIE generation 2 and has the capability of running at 5Gbps if connected to a PCIE generation 2 bus.

In this case the card is negotiating down to match the speed of the internal PCIE bus in the server.

There is no issue here, the card is working as designed.

To determine what bus speed you have in the server you need to refer to the server documentation.

Symptoms

We have a pair of QLE 8142s installed in a Sun T5220. For some reason both adapters are negotiating a bus speed of 2.5Gbp/s vs. 5.0Gbp/s:

PCIe Max Bus Width : x8
PCIe Max Bus Speed : 5.0 Gbps
PCIe Negotiated Width : x4
PCIe Negotiated Speed : 2.5 Gbps
HBA Status : Online

How can we get the adapters to run at 5Gbp/s?

Changes

 Installing a PCIE Generation 2 hba into a server that has only PCIE Generation 1 slots.

Cause

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