The Technoblog

Most of modern hard drives support a function called AAM (Automatic Acoustic Management), often disabled by default. Noise reduction is obtained by reducing the head speed, thus increasing the disk access time. If you prefer silence over performance you might want to enable AAM to decrease the noise level of your hard drive and slightly increase the access time.

Note that access time is about moving the head, not transfering data. So, activating AAM may have no impact to your overall system at all. Highest performance impact reported is around -5%.Thus, for a desktop computer (or notebook), it’s wise to enable AAM. In addition, enabling AAM (and thus reducing head speed) has a good side-effect: reduce the disk power consumption, especially interesting for a laptop.

Choose the best value for AAM by tweaking around the recommended one, depending on the silent level you target. Possible values depend on the drive itself (maybe from zero to 254, or only two states: 128 or 254 for instance).

Howto Enable AAM on a computer

Just download the freeware Hitachi Feature Tool, and run the setup tool to generate a bootable floppy or CD. Then, boot your computer over the created media to start the IBM/Hitachi Feature Tool. This tool makes it possible to enable, disable or choose a custom value for the Automatic Accustic Management feature, for any disk brand (not only Hitachi).

Howto enable AAM on a Linux box

Under Linux, you will need the hdparm utility. It is included in most Linux distributions, but on some “boxes”, like the Synology NAS, you’ll need to install it first.

Then, setting AAM is as simple as:

#hdparm -M 128 /dev/hda

to set a value of 128 (rather quiet) for drive hda. The higher the value, the higher the speed (and thus the noise).

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