I'm using a Matrox 250 GB external firewire hard drive. It's 137 GB Full - with unedited footage. 96GB remains.

Is it wise to render edited scenes to the same hard drive? Is it okay that my source and destination are on the same drive. Does this cause problems or a loss in speed.

Opinions appreciated.

No problems, fine to do. You will loose speed ofcourse, since it will
need to read and write to the same drive. I've done a lot of
rendering on/to the same drive.

p.s. you will also increase fragmentation on that drive....

Thanks Rob. How do I increase fragmentation on that drive? Just go to drive and open disk defragmenter?

I expect my edit to be about 40 GB max, whereas I have 96 left.

Decrease fragmentation, you want to decrease it <g>

Right-click on a drive in my computer and select properties. Go into
the tools tab. There will be a button Defragment Now. Another way
is to go to your administrative tools and open computer management.
The disk defragmenter is under storage.

yeah, sorry I got confused there for a second. You meant that rendering edited scenes to the same hard drive the footage is on will increase fragmentation...

Would you have recommended de-fragging now if I hadn't asked how to do it... should I leave de-fragging until I experience problems?

Thanks again!

I personally would leave defragging until you have finished your project. De-fragging can take a while with extremely large files on a disk.

You could of course analyse before you defrag that way you will find out whether you would need to do it or not.

Executive Software's Diskkeeper would be a good investment. Its an enhanced version of the disk defragger that comes with windows, but allows for scheduling, defragging the windows swap file, etc... I keep mine set to continiously defrag if I'm not using the computer. costs about $30 or $40.

Hmm... basicly you are OK to read&write to same drive but add to that it's external... - double bottle neck for the speed (although good external interfaces doesn't limit the hardrive phisical speed). But again the FireWire connection should work in both directions so really doesn't sound clever.
Don't you have some space on internal drives to schedule your render to there. Don't be afraid to use the drive with the OS&programs (the system one). It wont hurt performance as most things are executed from the RAM anyway.

I don't have so much space on internal drive that I could be comfortable. I don't mind if rendering takes longer using the external drive, due to the fact that I am also sourcing footage from it. Just needed to know if I would create other problems.. but I think it will be okay.