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| author | Guenter Roeck <linux@roeck-us.net> | 2020-08-08 18:07:10 -0700 |
|---|---|---|
| committer | Guenter Roeck <linux@roeck-us.net> | 2020-09-23 09:42:39 -0700 |
| commit | e40358390928f9ab9d8d7dde5c60c08981dc1d81 (patch) | |
| tree | 02d868700b3a2bcac73edea09b05e50d07474fda | |
| parent | 787c095edaa9de28d39671282eba7bddd479c038 (diff) | |
| download | linux-e40358390928f9ab9d8d7dde5c60c08981dc1d81.tar.gz | |
hwmon: (drivetemp) Add usage not describing impact on drive spin-down
On some drives, reading the drive temperature resets the drive's
spin-down timer. If the drive temperature is read too often, affected
drives will never spin down. Add this information as usage note to
the driver documentation.
Reported-by: Peter Sulyok <peter@sulyok.net>
Cc: Peter Sulyok <peter@sulyok.net>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
| -rw-r--r-- | Documentation/hwmon/drivetemp.rst | 18 |
1 files changed, 18 insertions, 0 deletions
diff --git a/Documentation/hwmon/drivetemp.rst b/Documentation/hwmon/drivetemp.rst index 2d37d049247f..0b1cf2f912c5 100644 --- a/Documentation/hwmon/drivetemp.rst +++ b/Documentation/hwmon/drivetemp.rst @@ -30,6 +30,24 @@ Transport is not supported, the driver uses SMART attributes to read the drive temperature. +Usage Note +---------- + +Reading the drive temperature may reset the spin down timer on some drives. +This has been observed with WD120EFAX drives, but may be seen with other +drives as well. The same behavior is observed if the 'hdtemp' or 'smartd' +tools are used to access the drive. +With the WD120EFAX drive, reading the drive temperature using the drivetemp +driver is still possible _after_ it transitioned to standby mode, and +reading the drive temperature in this mode will not cause the drive to +change its mode (meaning the drive will not spin up). It is unknown if other +drives experience similar behavior. + +A known workaround for WD120EFAX drives is to read the drive temperature at +intervals larger than twice the spin-down time. Otherwise affected drives +will never spin down. + + Sysfs entries ------------- |