FCS advantages to using external Hard drive as scratch disk?

rule #1 of video editing is never edit media that resides on the same drive as the OS... it is a speed issue (and to a lesser degree a stability issue).

Hi,

One of the reasons is that the video data is a continous stream of data. While editiing and capturing.

The system disk is also busy with the programm (FCP) and the OS (swapping, internal maintenance etc). So it can happen that while capturing the disk is used for other data exchange and FCP cannot deliver its data (dropped frames). It cannot be predicted when this happens. Same can happen while editing, but then at least you have the data correctly on disk.

So, as already stated by the big boss, always a seperate scratch/data disk. Spead issue but it also prevents errors and lost frames.

aside from the obvious - projects are not on the OS drive where the drive failure is most likely to occur - there are a few other things such as seek time, overall system performance/response time etc. its not like you would REALLY notice a difference in processing times etc, but it all counts.

if you render a lot, then small writes/reads to the internal drive might reduce the life time of the drive overall - so an external would be a nice addition.

Not to mention, you'll find over time when editing video (especially HD video), your hard drive space will start to disappear rather quickly. For example, DV NTSC video (SD video from MiniDV cameras) and HDV consumes around 13GB of space per hour. AVCHD (once converted to ProRes 422 for editing) at 1080i60 or 1080p30 can consume over 60GB per hour. It adds up really fast.

Use your main boot drive for OS and applications and let a separate disk handle your scratch. External FW drives are relatively cheap.