From owner-freebsd-hackers@FreeBSD.ORG Tue Aug 23 12:04:48 2005 Return-Path: X-Original-To: freebsd-hackers@freebsd.org Delivered-To: freebsd-hackers@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 72B6516A41F for ; Tue, 23 Aug 2005 12:04:48 +0000 (GMT) (envelope-from anderson@centtech.com) Received: from mh2.centtech.com (moat3.centtech.com [207.200.51.50]) by mx1.FreeBSD.org (Postfix) with ESMTP id E3A5243D45 for ; Tue, 23 Aug 2005 12:04:47 +0000 (GMT) (envelope-from anderson@centtech.com) Received: from [10.177.171.220] (neutrino.centtech.com [10.177.171.220]) by mh2.centtech.com (8.13.1/8.13.1) with ESMTP id j7NC4ip5038482; Tue, 23 Aug 2005 07:04:44 -0500 (CDT) (envelope-from anderson@centtech.com) Message-ID: <430B10EC.1080006@centtech.com> Date: Tue, 23 Aug 2005 07:05:00 -0500 From: Eric Anderson User-Agent: Mozilla/5.0 (X11; U; FreeBSD i386; en-US; rv:1.7.10) Gecko/20050815 X-Accept-Language: en-us, en MIME-Version: 1.0 To: Gary Jennejohn References: <200508221720.j7MHKpNb022773@peedub.jennejohn.org> In-Reply-To: <200508221720.j7MHKpNb022773@peedub.jennejohn.org> Content-Type: text/plain; charset=ISO-8859-15; format=flowed Content-Transfer-Encoding: quoted-printable Cc: freebsd-hackers@freebsd.org Subject: Re: IBM Active Protection System Approach X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 23 Aug 2005 12:04:48 -0000 Gary Jennejohn wrote: > Borja Marcos writes: >=20 >>>S=F8ren Schmidt writes: >>>I think this will need to be tailored to the exact type of "mishap" =20 >>>one wants to protect against. >> >> I think that the main purpose of the shock detection system is =20 >>to allow data to be recovered from the disk in case the laptop is =20 >>broken. By parking the heads asap you can avoid damaging the plates =20 >>with the head. >> >> At least that's what I read. The disk won't be necessary usable =20 >>after being dropped, but at least the plates should be readable. >> >> In that case, priority number one would be a fast parking of the = >>head. However, it could lead to a worst-case data loss with =20 >>softupdates and the disk cache, isn't it? >> >=20 >=20 > It seems to me that the worst-case scenario, dropping the laptop, > would result in extremely high G-loading in microsecomds rather than > milliseconds. Not much can be done to save the disk in such a short > time. The idea is for the laptop to recognize when it has begun a fall or=20 other sudden change in acceleration, so it parks the heads well before=20 impact time. > A scenario where the user bumps the laptop while in use might be > helped, though. Eric --=20 ------------------------------------------------------------------------ Eric Anderson Sr. Systems Administrator Centaur Technology Anything that works is better than anything that doesn't. ------------------------------------------------------------------------