How can I control HDD spin down time?

Question

I have 2 HDDs in my PC. Ubuntu is turning off the secondary HDD very quickly after about 15 minutes, which is short for me. I need to control this time. How can I do it?

I tried GNOME power management but did not find it useful.

Answer 1

Have a look at hdparm.

From the manual (man hdparm on the command line):

-S Set the standby (spindown) timeout for the drive. This value is used by the drive to determine how long to wait (with no disk activity) before turning off the spindle motor to save power. Under such circumstances, the drive may take as long as 30 seconds to respond to a subsequent disk access, though most drives are much quicker. The encoding of the timeout value is somewhat peculiar. A value of zero means "timeouts are disabled": the device will not automatically enter standby mode. Values from 1 to 240 specify multiples of 5 seconds, yielding timeouts from 5 seconds to 20 minutes. Values from 241 to 251 specify from 1 to 11 units of 30 minutes, yielding timeouts from 30 minutes to 5.5 hours. A value of 252 signifies a timeout of 21 minutes. A value of 253 sets a vendor-defined timeout period between 8 and 12 hours, and the value 254 is reserved. 255 is interpreted as 21 minutes plus 15 seconds. Note that some older drives may have very different interpretations of these values.

So sudo hdparm -I /dev/sdb | grep level will show the current spindown value, for example:

Advanced power management level: 254

From the manual: 254 is reserved so I expect it to be Ubuntu's default (can anyone confirm/expand on this please?)

Example:

sudo hdparm -S 25 /dev/sdb = spindown after 25*5 seconds.

sudo hdparm -S 245 /dev/sdb = spindown after (245-240)*30 minutes.

Answer 2

I add something like:

@reboot sudo hdparm -S244 /dev/disk/by-uuid/71492809-e463-41fa-99e2-c09e9ca90c8e > /dev/null 2> /dev/null

to root's crontab. Using uuid is better I think because sda/sdb etc. seems to change with every reboot

Answer 3

If you're interested on do the hdparm's setting persistent between reboots, instead of adding it to the crontab, you can use the /etc/hdparm.conf. I have the following:

command_line {
    hdparm -s 25 /dev/disk/by-uuid/f6c52265-d89f-43a4-b03b-302c3dadb215 
}

Add that line replacing the uuid by yours, or also you may specify the device using /dev/sdX format.