Changes between Initial Version and Version 1 of Powermode

Timestamp:

Jul 30, 2009, 1:35:14 AM (15 years ago)

Author:

Gabriele Pohl

Comment:

Move page from old wiki to here

Powermode

@@ +1 @@
+== Powermanagement ==
+
+If you use a computer under control of power management, you should instruct {{{smartd}}} how to handle disks in low power mode.
+
+ATA disks have five different power states. In order of increasing power consumption they are: {{{'OFF'}}}, {{{'SLEEP'}}}, {{{'STANDBY'}}}, {{{'IDLE'}}}, and {{{'ACTIVE'}}}. Typically in the OFF, SLEEP, and STANDBY modes the disk's platters are not spinning. But usually, in response to SMART commands issued by {{{smartd}}}, the disk platters are spun up. So if this option is not used, then a disk which is in a low-power mode may be spun up and put into a higher-power mode when it is periodically polled by {{{smartd}}}.
+
+Note that if the disk is in SLEEP mode when {{{smartd}}} is started, then it won't respond to {{{smartd}}} commands, and so the disk won't be registered as a device for {{{smartd}}} to monitor. If a disk is in any other low-power mode, then the commands issued by {{{smartd}}} to register the disk will probably cause it to spin-up.
+
+=== {{{-n POWERMODE[,N][,q]}}} ===
+
+This ''nocheck'' Directive is used to prevent a disk from being spun-up when it is periodically polled by {{{smartd}}}. It specifies if {{{smartd}}}'s periodic checks should still be carried out when the device is in a low-power mode. It may be used to prevent a disk from being spun-up by periodic {{{smartd}}} polling.
+
+The allowed values of POWERMODE are:
+
+==== -n never ====
+{{{smartd}}} will poll (check) the device regardless of its power mode. This may cause a disk which is spun-down to be spun-up when '''smartd''' checks it. This is the default behavior if the '-n' Directive is not given.
+
+==== -n sleep ==== 
+check the device unless it is in SLEEP mode.
+
+==== -n standby ==== 
+check the device unless it is in SLEEP or STANDBY mode. In these modes most disks are not spinning, so if you want to prevent a laptop disk from spinning up each time that {{{smartd}}} polls, this is probably what you want.
+
+==== -n idle ==== 
+check the device unless it is in SLEEP, STANDBY or IDLE mode. In the IDLE state, most disks are still spinning, so this is probably not what you want.
+
+Maximum number of skipped checks (in a row) can be specified by appending positive number ',N' to POWERMODE (like '-n standby,15'). After N checks are skipped in a row, powermode is ignored and the check is performed anyway.
+
+When a periodic test is skipped, {{{smartd}}} normally writes an informal log message. The message can be suppressed by appending the option ',q' to POWERMODE (like '-n standby,q'). This prevents a laptop disk from spinning up due to this message.
+
+Both ',N' and ',q' can be specified together.