I'm trying to merge several large jpgs into a large tiff (BigTiff) using montage (ImageMagick 7.0.11 on windows 10). The process requires a large amount of disk space and I'm trying to use an external 2TB disk as the temp folder since my main drive maxes out and causes ImageMagick to quit. I tried using -define registry:temporary-path but it seems like ImageMagick is unable to access the disk for the temp files. I'm able to read and write files to the external disk using ImageMagick, I'm just having problems getting ImageMagick to use the disk for the temp files.
Here is the full command I'm using (D:\ is the external drive and I created a folder named tmp):
magick montage -define registry:temporary-path=D:\tmp -mode concatenate -tile 2x1 D:\a.jpg D:\b.jpg TIFF64:D:\merged.tiff
When I try to run the command I get the following errors immediately without anything being written to the disk:
montage: unable to extend cache 'D:\a.jpg': No space left on the device @ error/cache.c/OpenPixelCache/3906.
montage: unable to extend cache 'D:\b.jpg': No space left on the device @ error/cache.c/OpenPixelCache/3906.
montage: 'TIFF64:D:\merged.tiff' @ error/montage.c/MontageImageCommand/1806.
I found what the issue was. The external drive was formatted in FAT32 and ImageMagick was trying to write temp files larger than 4GB (temp file sizes ranged from 10-50 GB). Formatting the drive to exFAT fixed the issue.