Powerbook External HD Question

Question

I'm looking to add an External Hard drive to a Powerbook .There' s a Firewire 400 Slot and a Firewire 800 slot, but I believe they are on the same bus. The Firewire 400 gets taken up when we capture video. What is the best way to capture the video directly onto the external hard drive? I've heard mixed things about Daisy Chaining the External Hard Drive. I've also heard that I shouldn't expect good performance having the camera pluged into the 400 slot with the HD on the 800. Am I mistaken that the most reliable way to capture video directly to the HD is by using another firewire card in the PC Cardbus?
What do you suggest?

Answer 1

Ripped from http://www.adamwilt.com/Tidbits.html
FireWire Frustrations: FireWire 400 (FW400) has more than enough bandwidth even for dual-stream DV, yet plenty of problems can occur when running FireWire disks and FireWire cameras on the same bus. There are a few possible reasons for this:
* The FW bus can only run as fast as the slowest device on it. Although Macs, PCs, and most drives should be talking S400 (400 Mbit/sec), many cameras and decks, both consumer and pro, only support S100 or S200 speeds. If you hang an S100 deck on your bus, you've just cut max throughput by a factor of four.
* A DV stream runs about 29Mbit/sec (including audio, aux data, etc.). That's nearly 1/3 of the usable bandwidth on an S100 FW bus, leaving only two raw streams' worth of bandwidth for disk I/O. However, due to the bursty nature of disk I/O, one needs about twice DV's data rate to ensure timely delivery of data--and that's with internal ATA drives. Given the "thin pipe" of the remaining 71 Mbit/sec bandwidth, playing/recording a single stream of DV while supporting DV I/O on the same bus is getting uncomfortably close to the limit.
* Some devices do not like to co-reside on a FW bus. Some Canon single-chip camcorders, Apple iSight webcams, and even some disk drives have been cited as "not playing well with others".
Many cameras / decks / converter boxes have used a very minimalist implementation of the 1394a spec, barely sufficient to find a compatible A/VC host on the bus and talk to it. Hence the oft-observed "baby duckling syndrome": hook up two FireWire decks to a Mac or PC, turn 'em on, and the first thing each one sees is mommy. Sometimes the decks talk to each other, ignoring the computer, sometimes one talks to the computer and the other is ignored, etc.
FireWire bridge chips in disk housings have comparable pathologies. Folks report that some drives work well on the end of a daisy chain but not in the middle of a daisy-chain, for example.
All these same caveats also apply when using a FW800 bus, of course.
I routinely play/record using a 7200rpm IBM DeskStar in a three-year-old ADS Pyro case using the Oxford 900 chipset with a Sony DSR-11, DHR-1000, or PD150 daisy-chained off it on an 800 MHz TiBook. I'm just lucky in that all this stuff happens to play nicely together. Your mileage may vary, depending on what equipment you're using.
Also note that using a common, low-cost FireWire hub will not help solve these sorts of problems. The best workaround I know of is to segregate disks on one bus, and your DV device on another. If you have a desktop or tower computer, you can add a PCI FireWire card; if you have a laptop with a CardBus slot, adding a CardBus FireWire adapter is the way to go.
G5 Dual 2.0 4GB RAM, 74GB Raptor, DVX100B, DSR-11   Mac OS X (10.4.7)