Exactly ... an "autosave" is just a timestamped copy of your project that is saved in the background whilst you work ... you can define how often you want this to happen and how many autosaved project files to retain in your FCP User Preferences.

Autosave files are relatively small, even in large projects - I've had projects with 2TB of media (don't ask...) and 20 or more Timelines/Sequences and the Autosaves were a couple of MB but are really only the Project file, no media associated or anything (ie. it's not an ARCHIVE)

As well, a few MB here, a few MB there REALLY adds up if you Autosave every 10 minutes or something... I clean up my Autosave vault out every couple of weeks and get back a couple hundred MB or MAYBE a GB or two, depending on how actively I've been editing.

Doesn't RAID-ing in software take a performance hit on the CPU's?

For hardware RAID configurations, what options are there for a 2009 Mac Pro?

Andrew, yes, but it's still way faster than a non-RAIDed option (my Apple software RAID 0 for drives 3 & 4) and back in Spring of last year (when I bought my Nehalem MP) all the advice I had on here was that the Apple RAID card was a pile of junk anyway (and as I recall, was not even compatible with the then brand new Nehalem's at that time). This may have changed (hopefully on both counts) and there are 3rd party solutions that many use of course - others with a deep understanding of Apple's current MPs (or at least 2009 onwards) and these 3rd party hardware set-ups will have to advise you.

All I can say is my system works really well - but if I was setting it up again I'd probably RAID 0 with three of the drives, not two (i.e. as per Dave's set-up). Maybe when I eventually upgrade to Snow Leopard I'll reconfigure it all - but that needs a gap in all my corporate film work and as we say over here, if it ain't broke don't fix it! (especially in the middle of important projects!). I'd probably stick with 1 TB drives, personally, as 2 TB ones might chuck out a lot more heat/forcing the MP fan on a lot more (mine is whisper quiet, rarely gets beyond a low purr even in major edits - which is great!).

Thanks for the info. Andy!!

What do you all think about the following configuration?:

HDD1 = OS, Apps
HDD2 = Media, Projects
HDD3 = Pagefile, Media Cache
HDD4 = Previews, Exports

Good? Bad?

While it may be the counsel of perfection to suggest a RAID-0 array I do wonder if nowadays with the capacity & performance of current disk models that it is really necessary.

At my wife's insistence because of the noise I removed the two disk external RAID-0 arrays that were the media & scratch locations on her edit station (8-core 2008 Mac Pro) & reverted to using the internal 2TB disks. The office is now much quieter & I can see no difference in the performance of FCP or render times. Maybe with complex projects with many HD video streams RAID-0 would be an advantage but considering many people seem to get by using FCP with a MacBook Pro plus at most an external Firewire disk then for many regular users configuring a Mac Pro with the I/O simply spread over four disks should be ample.

The reason I went with RAID 0 (internally) is that I kept running out of room on one 2TB drive or another while still having room on the others. Putting them together in to a 6TB RAID 0 completely fixed that problem for me AND had the advantage of faster throughput.

I agree about trying to keep external storage to a minimum. It helps with noise, power usage and heat too!

A simple RAID 0 takes almost no CPU time at all (nano seconds). If you were using RAID 5 (or similar) then that would be a completely different matter.