Originally Posted by unboggling
I guess I need to buy a book with discussion of temp files, symlinks, and ramdisks on OS X Mountain Lion.
For now I'm not using ramdisk until I know what I'm doing.
On Windows and Linux (and I presume on MacOS as well) you can over-ride Calibre using the system /tmp by setting the CALIBRE_TEMP environment variable to point to where you want Calibre to put its temporary files. This might save you doing some research and shoudl certainly be quick to try?