Inferring SAS expander topology

[Scott Long]

Hi Dustin,

FreeBSD relies on the LSI firmware to manage topology, and has no awareness of it on these controllers.  You can send SMP commands directly via the camcontrol utility and perform topology management and discovery manually.   I’m not sure if sg3_utils knows how to communicate with this, though.

Scott

> On May 30, 2017, at 11:00 AM, Dustin Wenz <dustinwenz at ebureau.com> wrote:
> 
> I'm working on a server that has 6 LSI SAS expanders connected to it. Two of them are throwing intermittent command errors and need some attention. Because the host only has four external 8088 ports, I know some of the expanders are chained through each other.
> 
> Before I can send parts for replacement, I need to determine if the two problematic expanders are either daisy-chained or directly connected to the host. On Linux, this is trivial; I would just browse the device topology in /sys/. However, this machine is running FreeBSD 10.3, and I am unable to find a way to do this. I have sg3_utils available, as well as any build-in FreeBSD tools. Using this software, is it possible to determine if a SAS expander is chained off of another?
> 
> 	- .Dustin
> 
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