From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tejun Heo Subject: Re: [PATCH 4/4 v2] Add documentation for hard disk shockprotection interface Date: Sat, 20 Sep 2008 19:25:09 -0400 Message-ID: <48D58655.5060300@kernel.org> References: <87d4j2n3dn.fsf@denkblock.local> <20080917163145.9870.8575.stgit@denkblock.local> <1221724782.3261.13.camel@raz> <87iqssmpl0.fsf@denkblock.local> <1221854586.7473.16.camel@raz> <87ej3f7pwr.fsf@denkblock.local> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: Received: from hera.kernel.org ([140.211.167.34]:56065 "EHLO hera.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751519AbYITX0r (ORCPT ); Sat, 20 Sep 2008 19:26:47 -0400 In-Reply-To: <87ej3f7pwr.fsf@denkblock.local> Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: Elias Oltmanns Cc: raz ben yehuda , linux-ide@vger.kernel.org Hello, Elias Oltmanns wrote: > Disk head parking is meant as a short term emergency resort. In general, > it does *not* extend the lifetime of a disk. In fact, emergency head > unloads are considered to be costly and smart even counts those events > as an aging factor. It really is just a means to prevent even worse > damage due to heavy shocks, nothing for regular maintenance. Just slight clarification. Emergency head unload has nothing much to do with explicit head unload used for shock protection. Emergency head unload happens when the power is lost while the head is loaded, that is, when the power is turned off without preceding IDLE IMMEDIATE or STANDBYNOW. But other than that, AFAIK, Elias's statement is correct. It's unclear whether unloading the head or spinning down the drive would extend or shorten the lifetime of a disk. -- tejun