Type of drive makes no difference. The size of the spool file is highly dependent on the type of printer and what you are printing. For example, if you have a wide format printer and you are printing 40x60 inch prints, that's a big file. If you are printing 8x10 prints on 8.5 x 11 paper, that will be smaller. The current printer driver resolution matters too: 300, 360, 600, 720, etc. You can calculate it yourself if you like. An 8x10 print at 600 PPI would be (8*600)*(10*600)*3=86 MB. A 20x30 inch print at 720 PPI would be (20*720)*(30*720)*3=933 MB. And if you are printing two of them in your job, it's twice that: 1.8 GB. And so on. That's how much data Qimage is sending to the driver. There is some overhead in the spooler that will make the spool file a bit bigger than that but those numbers will get you in the ballpark.
Regards,
Mike
Thx for usefull feedback, Maarten