I honestly would not recommend raiding anything over 4TB per disk really... IF Mikee DID go with the HDD storage route using 6TB or even the more costly 8TB disks, even if they was using some fancy form of raid like Raid 6 or 0+1 or 1+0 or even 1+5, rebuild success rates plummet due to each drives own error correction. I forgot what exactly happens, but apparently once you start going above even 2TB, rebuilding arrays properly if drives do fail can be almost impossible, and it has to do with some sort of old standard for how many bad bits of this or that is acceptable or something another. I just know from experience, rebuilding large arrays (4TB per disk) is difficult, 6TB disks make it nearly impossible, 8TB disks, I am willing to bet that no one puts into RAID till manufactures get tighter standards for error recovery.
RAID is out of the question, but for archival, if the disks are being used separately, they would work perfectly fine.
In the end, Mikee, these are your basic options.
Build a new system that has a good x8 PCI-e slot, then obtain a SAS controller that has the proper external connection for the tape drive your looking at.
$400 or so for the system?
$200+ for the SAS controller
$??? for tapes
$600 for the tape drive
Build a new fairly cheap system that has several SATA ports on it that are compatible with 6TB disks, and skip the SAS controller since this is a one-time backup.
$600ish for the system
$424 per 6TB disk (looking at these as they are enterprise grade, though warranty sucks... WD Purples might be better, and are cheaper, Seagate ST6000NM0024 6TB 7200 RPM 128MB Cache SATA 6.0Gb/s 3.5" Enterprise Hard Drive Bare Drive - Newegg.com
I honestly didn't think we was talking over a few TB worth of storage as I never see tapes above 2TB in capacity, personally I have one tape drive here, and a tape, it's only 1.4TB and backing up to it, and restoring data from it takes all day/night. In this case, long-term, tapes would be better, just pray you never have to restore from tape, especially with this much data. Either case, a new system will be required IMO.
So, OP, you still wanna go tape? If so, this is pretty much the only "cheap" SAS controller you can get that should support the tape drive. http://www.newegg.com/Product/Produc...82E16816118143
Next in line would be this, but I have no experience with Areca as they tend to be VERY costly, so this card being cheap worries me, http://www.newegg.com/Product/Produc...82E16816151101
Before you go ordering a SAS controller, see if you can find some specs on the external connection of that tape drive, there are different types of external AND internal SAS connections. From what little I can find it LOOKS like the tape drive uses a SFF-8088
I honestly can't find much for that tape drive online, seems Dell doesn't have much about it published.
One last thing to note, with THAT much data, your going to have what, 18 tapes or so? You should seriously consider the storage location for those tapes, something that can block magnetic fields, because tapes can and do get corrupted just like floppy disks from even weak EMI and weak magnetic fields, where as an HDD needs something a bit stronger to corrupt the data, but with the HDD, just sitting for years on end can cause it to fail (I have yet to see a disk fail this way) due to the metal "welding" together, such as the bearings in the motor seizing to the casing due to slight differences in the metals. But they do make special cases for storing tapes, and HDDS that protect against EMI/Magnetics/moisture for archival purposes.