[Motmot] Problems with long term acquisition

[Andrew Straw]

Jon wrote:
> Hi Andrew,
>
> We have been having problems acquiring over extended periods of time
> (in the area of 24-48 hours). We seem to suffer a high rate of
> computer freezes and/or frame-rate drops. As it stands, we have our
> cameras hooked up to a relatively weak computer system (p3-1Ghz) and a
> firewire external 1TB hdd.
> My question is more of an request for advice... Do you think we will
> need a RAID0 to handle large (>600Gig) files with reasonable speed (no
> drop off)? 
Hi Jon,

Here in the Dickinson lab, Alice Robie has played with various means of 
long duration recordings, and I think her conclusion is that anything 
but an (e)SATA connection (and ext2/3 filesystem on linux) is asking for 
trouble. Also, if you have a firewire camera, a firewire disk is 
sub-optimal if it's plugged into the same firewire card. Finally, from 
the symptoms you describe it sounds like the problems are correlated 
with the disk getting full -- in that case a larger disk may help, as 
might a different filesystem. I don't think you need RAID0 for speed 
reasons, but in terms of the large disk solution, this could help.

> Or do you think that our troubles can be solved with a more
> recent computer (the reason that it is not hooked up to one is that we
> have computers with onboard video that have 'difficulties' with
> running fview).
>   
The latest release of fview has an option "set view interval" menu 
option in the View menu whose purpose is to help with this issue. Also, 
perhaps buying a cheap nvidia graphics card would help.

But, all in all, I think you're being limited by harddrive/filesystem 
speed and for the first 600 GB your computer can keep up, so I wouldn't 
suspect the computer as being the fundamental problem. That said, a 
faster computer might just be the band-aid solution (curing the symptom, 
not the cause) that could get you through...

> Or would it be possible to implement a file-partitioning feature that
> could start new files once a certain filesize has been reached
> (downside: this would mean manually linking tracks from one file to
> another, upside: minimize slowdowns for large files and background
> changes will be minimized [food shrinks sometimes and messes up the
> background calculation a little]).
>   
That wouldn't be hard, but I'd rather spend my energies developing a GUI 
plugin for the "micro .fmf" file format that I've developed. The format 
is already pretty well used for some other projects of ours, and all I'd 
need to do is get it working with FView. That being said, writing GUIs 
is some of the most painful and slow kind of programming, so I can't 
promise anything...

-- 
Andrew D. Straw, Ph.D.
California Institute of Technology
http://www.its.caltech.edu/~astraw/