Network user access to local disk to solve I/O throughput issue?

Question

Not sure if this is the best forum for this, but...
THE ISSUE:
I work at a small university and am responsible for the Mac network and video dept (only 1 xserve and about 20-odd clients). Anyway, everyone uses network accounts. I have 3 iMacs for Final Cut and so far everyone just captures to the server over gigabit ethernet. We're only using DV25 (~4MB/sec transfer) and it hasn't been an issue until this week. Now as people begin to stress more about final projects, however, and are spending more time, the suites are being used more during the same times. Even though the throughput is usually less than 10MB/sec, which (I think?) is well under what gigabit ethernet supports, we're consistently getting stalled video and dropped frames. We've often had multiple people working on projects (playback) simultaneously in the past, but never capturing simultaneously before. Also, another factor that may come into play, is my 3TB RAID 5 that they're using has become rather full at this point (down to 200MB) so perhaps read/write times are being affected?
Now, we're looking at adding 6 more Final Cut suites, which will potentially increase my throughput load by 200%, so I really need to find a solid solution (and fibre cards are not an option since they're iMacs--and we don't have that budget anyway).
THE QUESTION:
Since the issue seems to only occur while capturing and not during playback, it seems the easiest solution would be to give the editor group access to the local hard drive (and then copy from there to their network storage so they can work on any given station later) which I'm not sure how the best way to do this would be. OR, should gigabit ethernet be capable of sustaining the throughput I need and there's some other problem I should be looking at to fix that?
Related, if they do capture to the local disk (or even an external hard drive, which we may end up going to), is there some script or something that can be run every night to automatically copy files from X location on a local drive to Y location (say, a common media storage location) on the server RAID?

Answer 1

Hi
+". . . my 3TB RAID 5 that they're using has become rather full at this point (down to 200MB). . ."+
I think the problem you're currently seeing starts (and probably ends) here. Regardless of what your data comprises of the general rule of thumb is to make sure you keep at least 10% of free disk space for any hard drive let alone a RAID. Most people would generally recommend 15% for a RAID 5. A rough calculation based on your 3TB RAID would mean you should keep at least 300GB free. You're well below that unless 200MB is a typo? I'm surprised the whole thing has not ground to a halt?
Video Capture, Editing and Playback in a network home environment is always going to place a considerable strain on any network unless you've prepared the ground first. For example 60 seconds of RAW Video is roughly 200MB in size. Multiply this for a classroom of 16 and that's a lot of data. Even if you're not using hi-def you're still talking a lot of data.
There are better ways of doing this.
HTH?
Tony