1What: /sys/block/*/device/sw_activity 2Date: Jun, 2008 3KernelVersion: v2.6.27 4Contact: linux-ide@vger.kernel.org 5Description: 6 (RW) Used by drivers which support software controlled activity 7 LEDs. 8 9 It has the following valid values: 10 11 0 OFF - the LED is not activated on activity 12 1 BLINK_ON - the LED blinks on every 10ms when activity is 13 detected. 14 2 BLINK_OFF - the LED is on when idle, and blinks off 15 every 10ms when activity is detected. 16 17 Note that the user must turn sw_activity OFF it they wish to 18 control the activity LED via the em_message file. 19 20 21What: /sys/block/*/device/unload_heads 22Date: Sep, 2008 23KernelVersion: v2.6.28 24Contact: linux-ide@vger.kernel.org 25Description: 26 (RW) Hard disk shock protection 27 28 Writing an integer value to this file will take the heads of the 29 respective drive off the platter and block all I/O operations 30 for the specified number of milliseconds. 31 32 - If the device does not support the unload heads feature, 33 access is denied with -EOPNOTSUPP. 34 - The maximal value accepted for a timeout is 30000 35 milliseconds. 36 - A previously set timeout can be cancelled and disk can resume 37 normal operation immediately by specifying a timeout of 0. 38 - Some hard drives only comply with an earlier version of the 39 ATA standard, but support the unload feature nonetheless. 40 There is no safe way Linux can detect these devices, so this 41 is not enabled by default. If it is known that your device 42 does support the unload feature, then you can tell the kernel 43 to enable it by writing -1. It can be disabled again by 44 writing -2. 45 - Values below -2 are rejected with -EINVAL 46 47 For more information, see 48 Documentation/laptops/disk-shock-protection.txt 49 50 51What: /sys/block/*/device/ncq_prio_enable 52Date: Oct, 2016 53KernelVersion: v4.10 54Contact: linux-ide@vger.kernel.org 55Description: 56 (RW) Write to the file to turn on or off the SATA ncq (native 57 command queueing) support. By default this feature is turned 58 off. 59