Here are some answers to the best of my ability.
(1) How many IOPS will Orion typically generate for the SQL server?
not sure of a number but it will be considerable especially if you use netflow, most of the larger installs in my opinion will need a seperate SQL server (thats what we did)
(2) Will the SQL DB be an OLTP or a DSS type system?
(3) Can a typical % split be estimated between read and write activity?
from what I have seen and I have watched this a lot is write activity is high but nothing crazy whereas read activity is VERY high. I would say 25% write / 75% read
(4) Does Orion use the tempdb at all, and if so, how heavily?
yes and fairly heavily , mine is on a seperate drive
(5) What kind of backup is recommended for the Orion DB, full, diff, or log?
We just do a full every night with TSM
Thanks for the info Donald. Any ideas about the OLTP vs DSS question?