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--- doc:appunti:hardware:raspberrypi_nas_smart_hard_disk [2021/04/16 17:17] – [hdparm] niccolo
+++ doc:appunti:hardware:raspberrypi_nas_smart_hard_disk [2025/10/08 06:59] (current) – [hdparm] niccolo
@@ Line 93: / Line 93: @@
 ===== hdparm =====
-To set the **Advanced Power Management** level use the **%%-B%%** option, the maximum performance level which **permits spin-down** of the drive is 127:
+To set the **Advanced Power Management** level use the **%%-B%%** option. A low value means aggressive power management, an high value means better performance. The maximum performance level which **permits spin-down** of the drive is 127:
 <code>
@@ Line 113: / Line 113: @@
 </code>
-Debian provides the file **/etc/hdparm.conf** which is handled by the **udev** on system start to set the required parameters. You can set something like this:
+Debian provides the file **/etc/hdparm.conf** which is handled by the **udev** on **system start** to set the required parameters. You can set something like this:
 <file>
@@ Line 119: / Line 119: @@
 # It is advisable to disable write cache in this case.
 # See man hdparm(8), -S and -W options.
+# The granularity of the spindown_time up to 20 minutes is 5
+# seconds, above that threshold it is 30 minutes.
 /dev/sda {
         write_cache = off
@@ Line 158: / Line 160: @@
   * **updatedb** - Execute by the **/etc/cron.daily/mlocate** cronjob, will update the database of files stored on hard disk. Add the directory to be skipped into **/etc/updatedb.conf**.
-  * **smartctl** - Reading SMART attributes (e.g. disk temperature, errors log) awake the disk. Hou may have periodic checks executed by **snmpd**, etc.
+  * **smartctl** - Reading SMART attributes (e.g. disk temperature, errors log) awake the disk. You may have periodic checks executed by **snmpd**, etc.
 ===== Web References =====