We do a lot of Intel serverboards, but don't use software Raid like ESRT2 much at all, due to its need for (and therefore vuneralbility to) OS-level support for correct operation. We either use the midplane + activation key Raid (eg. with SR2500LX), or add-in Raid card (eg. SRCSASJV, ala LSI8888ELP) with SSR212MC2.

The active midplane without activation key ("LSI IT/IR" Raid) may be supported by DSS, would have to verify this. The optional 2 x 2.5" kit for the new SR2600 chassis (eg. SR2620URLX) gives another option, tho you loose the 6th 3.5" drive bay, but I guess that would require the unsupported ERST2 again. Mmmmm. Next option (and they suggest this in the readme), is to create a small Raid array/vd within your main storage Raid array. Eg. if using a single R5, you would 1st create a little 2GB Raid array/vd across the disk group, then allocate the rest for the main array/vd. This config would be fully supported. Cheers.