daisy Disk says it is something called "sleepimage" and i have absolutely no idea what that is.
Anyone else know what this is?
That file is related to the sleep mode active on your Mac. See the explanation below. You probably have hibernation mode 3 active, which uses the sleepimage file.
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pmset -g
will list all the current power settings/device settings.
man pmset
Shows all of the manual for the pmset command
You can also check which mode your Mac is in by running this command:
pmset -g | grep hibernatemode
1. set hibernate mode to 0
sudo pmset -a hibernatemode 0
hibernationmode 0 is normal sleep, kept in ram nothing written to hdd
hibernationmode 3 is safe sleep, kept and loaded from ram, written to hdd in case of power loss
hibernationmode 25 is full hibernation, memory is written to hdd and then ram is powered off
Manual says mode 1 (and 5) are "not recommended"
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2. If you use hibernatemode 0, you can delete the unnecessary sleep file to regain disk space equal to memory (saves the same amount of disk space as your RAM, eg. 8 GBs), since hibernate is disabled.
if you want to reclaim the space the hibernate file takes up (valuable on an SSD), you can use the "Go" Menu and "Go to folder" for that. The file is found in the /var/vm/ folder, and is named sleepimage. Reboot and simply delete that file,. Or use this:
sudo rm /var/vm/sleepfile
