Re: Amount of time to back up to tape
LTO-6 drives are either SAS or FC (some expensive models, usually tape libraries, use Ethernet with link aggregation support).
For LTO-6 the uncompressed native transfer rate is sustained 160MB/s when reading as well writing.
Which means a 2,500,000MByte tape (actually just like with HDUs and SSD and CD/DVD/BD the real size it's base 2 not base 10...but then marketing... ) as written on IBM website: http://publib.boulder.ibm.com/infocenter/ts3500tl/v1r0/index.jsp?topic=%2Fcom.ibm.storage.ts3500.doc%2Fipg_3584_meltoworm.html
"Ultrium 6 2500 GB (2328.31 GiB)"
So it means 2,328,310 MB / 160 MB = 14551.9375 secs = 242 minutes = 4 hours 2 minutes approx
We can expect LTO-7 6.4TB tapes then to take: 6,250,000 MB / 315 MB = 19841 secs = 330 minutes = 5 hours 30minutes approx
For up to LTO-4 120MB/s standard consumer grade cheap SATA 7200rpm Hard Drives currently sold are more than enough .. even LTO-5 at 140MB/s could work...
For LTO-6 at least use two consumer grade drives in RAID-0 better on an hardware RAID controller anyway.
Obviously for professional use it's common to use no less than 8 HDUs in RAID-5 or RAID-6 .. otherwise for 16+ drives RAID-60 it's a better option. With hardware controllers supporting SSD caching then adding up to 4 SSD MLC or SLC drives for speeding the arrays up even further it's a good thing.