I'm not sure whether to post this here or on the FCP forum. Will try here first.
I'm running a c. two-year old Intel 2 GHz Intel Core Duo and booting off an external 500 Gb FW drive running Leopard (and sometimes off a 250 Gb internal drive running Tiger).
A few months ago two Seagate external drives (a 1500 Gb and a 500 Gb) were behaving erratically, and I was advised that Apple machines or OS's have difficulty with FW drives bigger than 1000 Gb. To its credit Seagate replaced both malfunctioning drives and agreed to give me two new drives (a 1000 Gb and a 500 Gb) to substitute for the 1500 Gb. Since then the system operates OK, except when I switch on other FW (400) drives daisy chained on without shutting down the unit first.
MY QUESTION: At this time, running Leopard (preferably) or Snow Leopard, can I add or substitute 1500 Gb or 2000 Gb FW drives for either the external boot drive or the external storage drives (or the internal boot HD) without erratic behavior? AND ANOTHER QUESTION: How many FW drives can I run without compromising stability?
While I haven't been booting from external drives, I've been using them for years as media drives for FCP and the like. I've used all kinds of drives fro 250gb up through 3TB drives with no problems; I don't think there is a Mac OS limitation to sizes of external drives. I've had a 8TB Drobo external drive connected to my Mac Pro for over a year and have had zero issues.
I see no problem with upgrading to any size drive either externally or internally (I currently run 4, 1TB drives in my Mac Pro).
As far as how many drives you can hook-up. You can daisy chain as many drives as you want, assuming you have enough power. I may be mistaken, but unless you RAID those drives, you will see a performance decrease as you add more and more drives simply do to the limitation of the transfer speed of the connection type, FW400, FW800, ESATA or whatever.