[Vis5d-users] Re: 2 GB file size limit

Subject: Re: 2 GB file size limit


> Don Middleton writes:
>  > We routinely create and visualize >2GB files with Vis5D. Long ago, I
added
>  > explicit code to the file handling module to accomodate this. Since
then,
>  > Jeff Boote has integrated our stereo3D, largefile, and VRML support
into the
>  > 5.2 release. I'm pretty sure that large files are handled just fine in
here
>  > (differently, using Posix contstructs instead of SGI extensions, I
think),
>  > but I'm cc'ing Jeff on this 'cause I haven't tried it myself. The
software
>  > is available at:
>  >
>  >             http://www.scd.ucar.edu/vg/SoftwareSystems.html
>  >
>
> Sorry for the sarcasm in my last mail, but I thought, that the hole
> vis5d-file is loaded into memory if it gets visualized. Isn't this
> true? And if the OS starts swapping isn't the rendering considerably
> slowed down? Just wondering, haven't tried it yet.

Our SGI systems have 7-8GB of physical memory and in the past I've
configured swap for 50GB or so, as I recall. If you swap things of course
slow down. If you traverse your dataset linearly it can be livable. If you
let a "make_isosurface" run on multiple processors on a large dataset it can
be horrific. I always run Vis5D in "verylarge" mode and, more often than
not, with an option to turn off multi-processing. I don't know if Vis5D
actually loads the entire dataset at startup time or not - it may just
allocate the memory. Even with very large datasets, it starts up quite fast.

don