From: John Stone (johns_at_ks.uiuc.edu)
Date: Wed Dec 16 2020 - 20:32:27 CST

Jason,
  Interesting. It's possible that I need to enable additional special
compile-time macros to ensure that the molfile plugins don't get
restricted to small-file-addressing limitations on Windows. On 32-bit Windows
I had to do a bunch of special code to work around this.

I have loaded some very large tomograms in the 64-bit VMD build with
multi-gigabyte density maps, so I'll have to have a closer look
at the DCD plugin in particular since that's the case you're
running into. Different molfile plugins use different I/O APIs,
making some of this a bit tricky since they have to be checked on
a case-by-case basis when this kind of limitation occurs.

Best,
  John Stone
  vmd_at_ks.uiuc.edu

On Thu, Dec 17, 2020 at 01:35:18AM +0000, Jason Smith wrote:
> Hi,
>
> just installed this today (vmd194a50win64-SetupV3) and have been unable to
> open large trajectories :(. BTW I am very very excited to be able to
> address larger amounts of memory on a 64-bit version. Thank You!
>
> Through some trial and error it seems like the problem lies in the file
> size, not whether the file fits in memory. For e.g.
>
> 977 MB file in a50 opens, a 2.9 GB does not (28 GB free memory, 32
> installed). For 1.9.3 in the past I always found it would crash when
> trying to use more than around 1.1 - 1.3 GB of memory.
>
> What's more is that I can't use frame striding to get around it. In 1.9.3
> and 4a48 I can open up my 100 GB files using striding, but I can't open
> the 2.9 GB in a50 using striding.
>
> I also repeatedly opened a 750 MB DCD in a50 until task manager indicated
> 4.5 GB usage by VMD, so not a 32-bit memory limit. I also tried to open
> the files from HDD vs NVME in case it was a hardware issue.
>
> The error given is:
>
> dcdplugin) Could not access file 'E:/temp/6yb7_NPT_Production-2.dcd'.
> ERROR) Could not read file E:/temp/6yb7_NPT_Production-2.dcd
>
> Cheers,
>
> -
> Jason Smith
> Post-Doctoral Fellow
> Robert N. Young Lab, Simon Fraser University
> 8888 University Drive, Burnaby, BC, V5A-1S6
> Canada

-- 
NIH Center for Macromolecular Modeling and Bioinformatics
Beckman Institute for Advanced Science and Technology
University of Illinois, 405 N. Mathews Ave, Urbana, IL 61801
http://www.ks.uiuc.edu/~johns/           Phone: 217-244-3349
http://www.ks.uiuc.edu/Research/vmd/