[CentOS] low end file server with h/w RAID - recommendations

>Most servers can fit only 2.5" disks these days.  I keep wondering what everyone is doing about storage.

The DL20 gen9 I bought was setup LFF (3.5")

The DL380 gen9 could be either SFF (2.5) or LFF. I had to buy SFF for our new server due I was told to spec / build it exact to vendor recommendation.

To better? Answer this. Agreed, I'm not a fanboy of 2.5" stuff in enterprise equipment. To me a better but more costly answer would be setup a LFF SAN server and go from there. 

My employer is a SMB (60 people?) and our storage is exploding at times. SAN's can give more economical storage and flexibility. Especially since were considering fail-over scenarios for not only our Windows ERP software but our all Linux based :) file servers.

Regards,

Richard