Bruce Allen says that 254 should disable power management while the behaviour of 255 is unpredictable. Strangely not only hdparm's man page but also doing the command tells us that you should use 255 to disable power management :
$ sudo hdparm -B 255 /dev/sda /dev/sda: setting Advanced Power Management level to disabled $ sudo hdparm -B 254 /dev/sda /dev/sda: setting Advanced Power Management level to 0xfe (254) -- Hard drive spindown should be configurable https://bugs.launchpad.net/bugs/17216 You received this bug notification because you are a member of Ubuntu Bugs, which is a direct subscriber. -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
