DAS arrays are extremely easy to understand, they're just "expanders" - SAS has special support built in for this, in servers you typically have the front drive bays connected to a single SAS port on the board instead of individual cables running to each drive, a DAS is the same thing just as an external enclosure with separate power. You connect it to a basic SAS HBA with an external SAS port (SFF-8088), like the LSI 9200-8e I mentioned and it just shows up as a bunch of drives to your operating system. There's some special control services you have to the enclosure depending on the model through a protocol called SAS Enclosure Services (SES), my Lenovo SA120 uses this to manage things like fan speeds (very important, because every time it loses power it resets to HIGH which is VERY LOUD, I have a boot script on my FreeNAS box to set this back down to LOW which is much more manageable).
This seems like a lot, but you can ignore most of the technical details I just posted. Buy a SAS HBA with external ports, buy a SAS DAS array, plug it in and you see a bunch of drives - no fuss. Since SAS controllers can also support SATA drives you can save yourself $10-20 a drive and buy normal SATA disks, or you can get some added reliability (multi-pathing and error handling) and buy near-line SAS drives for a small premium (I don't bother personally, but I only have one controller installed in my SA120 so I have no second path for data to travel in the event of a failure anyway).
Feel free to hit me up anytime, I'm /u/snuxoll on reddit (pretty active on /r/homelab) and you can email me at stefan [a] nuxoll.me.
This seems like a lot, but you can ignore most of the technical details I just posted. Buy a SAS HBA with external ports, buy a SAS DAS array, plug it in and you see a bunch of drives - no fuss. Since SAS controllers can also support SATA drives you can save yourself $10-20 a drive and buy normal SATA disks, or you can get some added reliability (multi-pathing and error handling) and buy near-line SAS drives for a small premium (I don't bother personally, but I only have one controller installed in my SA120 so I have no second path for data to travel in the event of a failure anyway).
Feel free to hit me up anytime, I'm /u/snuxoll on reddit (pretty active on /r/homelab) and you can email me at stefan [a] nuxoll.me.