What does this command do? HBA issue?

SandMan
SandMan used Ask the Experts™
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Hi Experts,

Can anyone explain to me what this commands do? The XenServer engineer told me to do this command on my XenServer connected to a HBA Storage.

echo "options lpfc lpfc_use_msi=2" > /etc/modprobe.d/lpfc
then reboot the server
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Top Expert 2014

Commented:

Author

Commented:
Hi Andyalder,

Thanks for the reply. But can you explain in laymans term what is the purpose of that commands do and what can it do on my environment? Does it rescan or reconfigure the HBA connection?
Tony JohncockLead Technical Architect

Commented:
Here you go. Some XenServer specific details:

http://forums.citrix.com/message.jspa?messageID=1611385

It appears to correct a known issue with some HP servers & Emulex HBA's
Top Expert 2014

Commented:
You'll have to wait until I finish reading http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=blob;f=Documentation/PCI/MSI-HOWTO.txt and if you read it too you'll know as much as me!

It reconfigures the PCIe interupt type the card uses to communicate with the CPU/kernel, I may be wrong about the default being 2, if you have a PCIe 3.x card then the default mode may be different so it's quite possible you're being asked to set it to an older mode.

May I ask why the XenServer engineer asked you to change it?
Top Expert 2014
Commented:
http://h10025.www1.hp.com/ewfrf/wc/document?cc=uk&lc=en&dlc=en&docname=c02662375 links to some redhat docs on it too, doesn't explain the problem in detail.

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