From owner-freebsd-hackers@FreeBSD.ORG Thu Mar 12 11:30:23 2009 Return-Path: Delivered-To: freebsd-hackers@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id CA2DE1065673 for ; Thu, 12 Mar 2009 11:30:23 +0000 (UTC) (envelope-from tijl@ulyssis.org) Received: from mailrelay011.isp.belgacom.be (mailrelay011.isp.belgacom.be [195.238.6.178]) by mx1.freebsd.org (Postfix) with ESMTP id 66F7B8FC17 for ; Thu, 12 Mar 2009 11:30:23 +0000 (UTC) (envelope-from tijl@ulyssis.org) X-Belgacom-Dynamic: yes X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: AkIFAI6PuElR9Nhz/2dsb2JhbACBTtE7hA0G Received: from 115.216-244-81.adsl-dyn.isp.belgacom.be (HELO kalimero.kotnet.org) ([81.244.216.115]) by relay.skynet.be with ESMTP; 12 Mar 2009 12:30:21 +0100 Received: from kalimero.kotnet.org (kalimero.kotnet.org [127.0.0.1]) by kalimero.kotnet.org (8.14.3/8.14.3) with ESMTP id n2CBUHUU002395; Thu, 12 Mar 2009 12:30:17 +0100 (CET) (envelope-from tijl@ulyssis.org) From: Tijl Coosemans To: freebsd-hackers@freebsd.org Date: Thu, 12 Mar 2009 12:30:15 +0100 User-Agent: KMail/1.9.10 References: <200903050758.n257wod8088426@lurza.secnetix.de> <49B02211.1010809@abitos.org> In-Reply-To: <49B02211.1010809@abitos.org> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Content-Disposition: inline Message-Id: <200903121230.17041.tijl@ulyssis.org> Cc: Tobias Blersch , Oliver Fromme Subject: Re: Spin down HDD after disk sync or before power off 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: Thu, 12 Mar 2009 11:30:24 -0000 On Thursday 05 March 2009 20:03:45 Tobias Blersch wrote: > http://www.hitachigst.com/tech/techlib.nsf/techdocs/28DCCB17E0EEC5A086256= =464E006E2F5B >=20 > Thats the specification for my notebooks hard drive. Section 6.6 > Reliability gives data about how to power-off the disk. It also > contains numbers of supported load/unloads and emergency unloads. > Emergency unloads are invoked when the heads are still loaded and > power fails. Quoting that document: 10.4.1 Emergency unload (...) Emergency unload is intended to be invoked in rare situations. Because this operation is inherently uncontrolled, it is more mechanically stressful than a normal unload. A single emergency unload operation is more stressful than 100 normal unloads. Use of emergency unload reduces the start/stop life of the HDD at a rate at least 100X faster than that of normal unload, and may damage the HDD. 10.4.2 Required power-off sequence (...) You may then turn off the HDD in the following order: =E2=80=A2 Issue Standby Immediate or sleep command. =E2=80=A2 Wait until COMMAND COMPLETE STATUS is returned. (It may take up= to 350ms in typical case). =E2=80=A2 Terminate power to HDD. This power-down sequence should be followed for entry into any system power-down state, or system suspend state, or system hibernation state. In a robustly designed system, emergency unload is limited to rare scenarios such as battery removal during operation.