Help wiring MSA 2040 to 2040 disk shelf

[foodandbikes]

Hello,

This is my first experince with the MSA product, so please bear with my ignorance.

The customer ordered a MSA 2040 chassis with a single controller, and also a MSA 2040 shelf with 2 controllers.

From all the diags I am seeing, it looks like all shelves/chassis should have the same number of controllers. When wiring them together do I just run a cable from the OUT SAS port on the chassis, to the IN SAS port on the top controller on the shelf?

[Torsten.]

if there is a single array controller only, you can only connect a single expansion controller.

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[foodandbikes]

Thanks for the info.

So it souds like I won't be connecting anything into the second controller on the disk shelf. Now I have to wonder why it was ordered/sold this way.

[Torsten.]

you need 2 array controllers for better performance and redundency.

[foodandbikes]

Thanks.
If the disk shelf has 2 controllers, but the main chassis has 1, is there any benefit of having the second controller in the disk shelf?
I'll suggest getting a second controller for the chassis, but if they choose not to is the second controller in the disk shelf doing anything?

[Torsten.]

no, it is almost useless.

but maybe 99% of all arrays have dual controllers ...

[foodandbikes]

Great, thanks for the help.