Disk Drives

Does SATA ALPM cause disk corruption with Btrfs?

No. SATA ALPM has been safe since kernel 4.15.

Statement of BTRFS developer David Sterba: “It’s a hardware problem leading to filesystem corruption. It’s affecting all filesystem[s] but the detection capabilities differ, so it stuck with btrfs. […] the fixes to ATA subsystem have been merged to 4.15.”

Why is my HDD parking the read-write heads so frequently (clicking noises)?

The APM setting for battery mode


corresponds to the Ubuntu default and should cause no problems. Unfortunately drive vendors interpret the APM levels quite spaciously to save power.

Solution: try values > 128. See DISK_APM_LEVEL_ON_AC/BAT.

Why does my HDD not spin down?

Stopping the system disk for extended periods of time is unlikely to work, because applications and system daemons wake up the disk frequently. There is no real solution for this other than changing many applications and daemons.

How can I stop my 2nd HDD?

To spin down after 1 minute (= 12 · 5 seconds) idle time use:



Why does my HDD always spin up when switching from AC to battery power (and vice versa)?

TLP applies configured APM levels and spin down timeouts upon every change of power source and upon suspend/resume. Writing the settings inevitably spins up the disk. To prevent this behaviour either disable the settings completely by commenting all of them (with a leading #) or use the special value keep for the specific disk.


Why is my Crucial M4 SSD so slow on battery?

The Crucial M4 reduces performance according to the APM level. You may disable APM with


Drive Bay: why is the optical drive not powered off on battery?

Possible causes are:

ThinkPad without UltraBay

SL/Edge models for instance.

Incompatible Laptop

At the time of writing this functionality is tested with ThinkPads only.