G5 Hard disk setup
 

The new Apple G5 comes with the option of having two 250 gb Serial ATA hard drives "raided" together for video storage. The question that I have is if anyone is aware of the ability to add another hard drive to the G5 specifically for applications? Are you limited to only 2 drives? Is the video storage "raid" drive to be used for captured video and applications? I thought it was always preferable to have a separate drive for apps.

No, OS X is UNIX based and the system should always install the Apps in it's default location. Moving apps from the default location can cause major problems.

The RAID is a software RAID, I believe. My understanding is that the G5 has room for only 2 internal drives. External drives could be FireWire 800 or SCSI, for speed. FireWire 400 is an option also if all your doing is DV.

Software RAIDs are sometimes slower than a single drive. I would wait for some of the speed tests before jumping on the internal RAID bandwagon.

application drive
 

Just to give you a simple, straightforward answer, your applications have to be on your start-up volume -- the hard disk or hard disk partition that you have your system on. Video footage, still photos, audio clips, etc., should ideally be on separate media drives that are not running your system and applications. Given the limitation of two internal drives on the G5, I'm planning on installing a system, with all applications, on an external drive, and saving the two faster SATA internal drives for media. The external drive can be on the FW400 bus, no problem. In the G4's, even a few years ago, your FCP set up could have been to have the start-up drive (with system and applications) on a hard disk you hooked into slow (33Mhz) ATAPI 2nd optical bus.

An exotic alternative is to have the system and applications on a 2.5" drive onboard a Sonnet brand ATA PCI card, but you'd have to really verify with Sonnet that their card will work with the PCI slots of your G5. If you have a 1.6Ghz G5, then no problem, no need to check with Sonnet. If you have a faster G5, you had better check if Sonnet is sure their ATA card, with the slot for an on board HD, will work in either the 100Mhz or the 133Mhz PCI slots on those faster G5s.

Having your system and applications on an external FireWire 400 drive will slow down performance. I've seen it tried. Are you doing DV or uncompressed media? DV will not benefit by the faster internal drives. FireWire 400 and 800 are more than adequate for DV. A FireWire 800 RAID should do uncompressed video

Where to put system & apps?
 

Yes, you can put media on external FW drives. Yes, there is some performance hit when running the system and apps from an external firewire device. However, the performance that would be slowed is boot up, opening of an app, and finder functions such as duplicate or copy within the finder. Once FCP is open and in RAM, functions like capture, writing out to tape, rendering, and real time effects will not, to my knowledge, make calls on the system. In all those functions within FCP, faster access to your media drives is what determines speed, including issues such as how many layers of effects you'll be able to do in real time. That's where I'd like to put my speed, and that's why I am willing to trade off the speed hit in start-up and finder operations to make FCP work better and faster.

It will be quite interesting to see what 'add-ons' come out after the G5. It is disappointing they chose to cut down on the amount of internal HD space. However, there is yet another option for increasing HD storage beyond FW/USB2. You can add a PCI controller card a run the HD off of that. I have seen rumors of an expanion card with an external HD bay patterned after the G5. Not Apple but a third-party manufacturer.

For DV work my plans are simpler. One drive for apps, photos, etc. one drive for the project in hand. Once the project is done, dump it to an external drive and flush the internal. It gets around capture problems to the external drive that way.

I think if I was serious about working uncompressed I'd be waiting to see what a G5 xserve looked liked.....

Internal drives generate a lot of heat and a lot of noise. Apple is trying to limit both by limiting the internal drive space to two drives. Apple is also firmly committed to FireWire. By the time FireWire 3200 is implemented, uncompressed HD should be no problem.

The internal RAID is software based (at least from everything I've read). In many cases software based RAID configurations can be slower than a single drive. Software RAIDS tend to do poorly on sustained write tests of large files (think DV capture and render). Hardware RAIDS excel in this area. Software RAIDs do better on Random read and Sustained read tests. This is great for the Unix OS because the drives tend to get fairly fragmented.

I would wait for the experts to do the tests before I jump to the conclusion that the internal drives will be faster under all conditions.

This article in InfoWorld might also shed some light on Apple's design considerations and future plans.