SAS ports up and down on C190

[PeterMe]

Hello,

I'm looking for an explanation why on an AFF-C190 without a shelf, the SAS port 0a is down and the 0b is up.

thanks

 

[maffo]

AFF-C190 ship without SAS cables by default; 0a shows down as no cable is plugged in it however 0b shows up as it also provides connection to the internal shelf.

[andris · Accepted solution]

+1 for @maffo's response.

If you check the output of the nodeshell "sysconfig -v" command, you can see this clearly.

As a technical "tidbit", the physical SAS 0a port on the back of the controller is connected to an actual SAS HBA port chip.  The physical SAS 0b port on the back of the controller is connected to the internal shelf's SAS expander chip.  The SAS 0a HBA port chip is internally connected to the same SAS expander chip for direct access to all of the drives in the internal shelf.  That's why you see the <==> symbol beside the 0b port, to signify it being connected to the SAS expander chip.

[PeterMe]

@maffo and @andris

Thank you for the explanation