Hello, Could you please provide any custom settings you have in /etc/hdparm.conf ? What model is your HDD? Some new disks (I have seen it with some SSHD hybrid disks in particular) may not respond to certain SATA commands in the way one would expect.
Suggestions for debugging: Please be cautious when experimenting with hdparm values and make sure you have a good understanding of the settings you specify. It would be best to find out which hdparm setting freezes your hard drive. It might be the apm level. If you haven't set anything in the configuration file, it will try to set hdparm -B 254 as you don't have powermgmt-base installed, so AC power will be assumed. Try running commenting out the "quiet" keyword in the configuration file and then try running DEVNAME=/dev/sdX /lib/udev/hdparm as root manually (with the right drive instead of sdX) to find out if it prints any error messages. I hope this will help to resolve this issue. Kind regards, Ondřej Grover
