From owner-freebsd-hackers@FreeBSD.ORG Thu Sep 16 18:02:36 2010 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 5A78D1065672 for ; Thu, 16 Sep 2010 18:02:36 +0000 (UTC) (envelope-from rwmaillists@googlemail.com) Received: from mail-wy0-f182.google.com (mail-wy0-f182.google.com [74.125.82.182]) by mx1.freebsd.org (Postfix) with ESMTP id DC9ED8FC17 for ; Thu, 16 Sep 2010 18:02:35 +0000 (UTC) Received: by wyb33 with SMTP id 33so2135362wyb.13 for ; Thu, 16 Sep 2010 11:02:34 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=googlemail.com; s=gamma; h=domainkey-signature:received:received:date:from:to:subject :message-id:in-reply-to:references:x-mailer:mime-version :content-type:content-transfer-encoding; bh=KabAr2bqs7bh6gCNdZI1LiSGjqw1JKfmkzEmIKaVSBY=; b=Z1LuLy/zTiK2km6AA6WTrzC5LAUAYZEK6QVtsMeziuCDOJav8j6UYnxnRhb1nSf4Q1 8FX5PjhUDAnNJHS7TGNnZ0gzgHKoi6yUE3VkJpGu8IaJrz7JVSVjr0PFwI4D/pMdoMF3 x5ldIo1NM5oDkLiUiFgouATiKAfN/mUSa1ptc= DomainKey-Signature: a=rsa-sha1; c=nofws; d=googlemail.com; s=gamma; h=date:from:to:subject:message-id:in-reply-to:references:x-mailer :mime-version:content-type:content-transfer-encoding; b=BYx1Iq1QUR9JFR4J/vFEWFNnfVnJhgl50YvjVBR+vDmTA82XgpFQuQs3ZSNhFNgM5g boBartZaCkP02iCqpRfEjHAnWLFWmGcj8m7olznk1wG8+8+b5TVDWSeh/TRk2PgG5Htc k5ohRKQBactYA3efSvA0HaXQkbgzKf4OoKJOQ= Received: by 10.216.21.204 with SMTP id r54mr3001019wer.95.1284658266706; Thu, 16 Sep 2010 10:31:06 -0700 (PDT) Received: from gumby.homeunix.com (bb-87-81-140-128.ukonline.co.uk [87.81.140.128]) by mx.google.com with ESMTPS id p82sm2001464weq.3.2010.09.16.10.31.05 (version=SSLv3 cipher=RC4-MD5); Thu, 16 Sep 2010 10:31:05 -0700 (PDT) Date: Thu, 16 Sep 2010 18:31:03 +0100 From: RW To: freebsd-hackers@freebsd.org Message-ID: <20100916183103.20c70a5a@gumby.homeunix.com> In-Reply-To: <86mxri17j3.fsf@ds4.des.no> References: <201009152143.o8FLhE9p022233@lurza.secnetix.de> <20100916004902.GA46401@freebsd.org> <86mxri17j3.fsf@ds4.des.no> X-Mailer: Claws Mail 3.7.6 (GTK+ 2.20.1; i386-portbld-freebsd8.1) Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Subject: Re: Summary: 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, 16 Sep 2010 18:02:36 -0000 On Thu, 16 Sep 2010 09:17:52 +0200 Dag-Erling Sm=F8rgrav wrote: > Garrett Cooper writes: > > Agreed. Spinning down at reboot isn't smart and seems like a good > > way to kill a disk quicker. >=20 > *not* spinning down at halt is far worse. Most modern disks are rated > for hundreds of thousands of load-unload cycles, but far fewer > emergency unloads (which is what happens when the drive loses power > while still spinning). As I understand it wear from spinning-down used to come from the head actually scraping the disk surface as it lost lift, parking placed the head on a disposable area, but modern drives take the head off the disk altogether. When Hitachi was specifying 300,000 unloads, they said that in testing the drives were still working at 1,000,000, someone quoted 600,000 as the current spec. At these levels you can be spinning the drives down and up ever few minutes for the normal lifetime of the drive. Even on very old drives I doubt reboot are much of a problem, they're rare on servers. On laptops and desktops they're rare compared to shutdowns and suspends. =20