How can I improve memory allocation on my PC for Raster Manager?
1) Windows uses a paging file to run applications: this can be redirected to a disk with the most memory available. The size of the paging file can also be increased to improve application operation speeds. The setup is usually located under the Window's Start > Settings > Control Panel > System menu, you can also do a Windows search with "Paging" as the keyword for more info.
2) Raster Manager stores the image cache under the Window's temporary directory. You can change the location of the temporary directory to a disk with more free space.
3) Point the MS_TMP variable in MicroStation to a drive with more freespace.
https://communities.bentley.com/products/microstation/w/microstation__wiki/30565.how-to-increase-the-raster-available-memory