From mboxrd@z Thu Jan 1 00:00:00 1970 From: raz ben yehuda Subject: Re: [PATCH 4/4 v2] Add documentation for hard disk shockprotection interface Date: Fri, 19 Sep 2008 22:03:06 +0200 Message-ID: <1221854586.7473.16.camel@raz> References: <87d4j2n3dn.fsf@denkblock.local> <20080917163145.9870.8575.stgit@denkblock.local> <1221724782.3261.13.camel@raz> <87iqssmpl0.fsf@denkblock.local> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Return-path: Received: from fw.bitband.com ([213.8.50.174]:29807 "EHLO mail.bitband.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1754009AbYISUDK (ORCPT ); Fri, 19 Sep 2008 16:03:10 -0400 In-Reply-To: <87iqssmpl0.fsf@denkblock.local> Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: Elias Oltmanns Cc: linux-ide@vger.kernel.org On Fri, 2008-09-19 at 11:50 +0200, Elias Oltmanns wrote: > [ For some reason your email has not shown up on linux-ide. ] yes. I noticed too. > "Raz Ben-Yehuda" wrote: > > Elias > > looks very interesting. > > 1. How will it impact VM , swappers , raids ? > > What exactly do you want to know? As long as the disk is parked, you can > do no I/O on it, i.e. no swapping is possible. Since I don't know > anything about the implementation of raids and don't have a raid setup > here, I can't really tell how a raid device will behave exactly when one > of its disks has been parked. Generally, all I/O will be delayed until > the disk is unparked again. > > 2. you said it has no value for servers ? did you try ? > > Again, I'm not quite sure what you want to know. Obviously, desktops or > servers for that matter can have disks installed that support the unload > feature. On these devices you can use the interface as described in my > document. All I'm saying is that the interface has been designed with > laptops in mind because I don't see in which situation immediate head > unloading would be required or even desirable in a classical server > environment. I will rephrase. does head parking increase reliability ( MTBF ... MTTF ) of a disk ? My servers hardly generate IOs at night times, does head parking at nights extend the life of a disk ? or is it the opposite ? does it matter ? thank you again raz > Regards, > > Elias