How to use SAS Expander with RAID card?

Solution 1:

There's a lot of good information here about the HP SAS Expander.

Question that may help you are:

Do SAS expanders work transparently with SAS controllers?

How exactly does a SAS SFF-8087 breakout cable work? + RAID/connection questions

But in general, yes, you can use the HP SAS expander to link one controller to more disks than 2 SFF-8087 ports would natively provide. This, of course, only applies to internal SAS disks.

For the enclosure you linked, there are 6 SFF-8087 ports and no oversubscription. A SAS expander will be needed.

The definitive resource for the HP expander card you're interested in is here.

Solution 2:

Basically yes, you do either take a card with external ports or use a slot bracket like this one to connect an existing controller with internal-only ports:

The HP expander card would need to be powered through a PCIe slot. You could use an empty mainboard (no need for CPUs or RAM) attached to the PSU(s) of the chassis to make it work.

This article over at servethehome.com describes a project which is very similar to what you are trying to do. But to be honest, what you should be doing is buying a JBOD with the expander (preferably even two of them) already built into the backplane. You might want to look at Supermicro's SC846E26 for an example.

You also should do thorough testing with the controller / expander combination - expanders do not work (all that well) with SATA drives, so you might want to plan for SAS interposers as well. Additionally, specific RAID controllers may or may not work with expanders - make sure to check the spec sheet and bug the presales support.