From owner-freebsd-fs@FreeBSD.ORG Thu Dec 6 17:29:55 2007 Return-Path: Delivered-To: freebsd-fs@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id DB9A016A417 for ; Thu, 6 Dec 2007 17:29:55 +0000 (UTC) (envelope-from bg@sics.se) Received: from letter.sics.se (letter.sics.se [193.10.64.6]) by mx1.freebsd.org (Postfix) with ESMTP id A338513C447 for ; Thu, 6 Dec 2007 17:29:55 +0000 (UTC) (envelope-from bg@sics.se) Received: from sics.se (ibook.sics.se [193.10.66.104]) by letter.sics.se (Postfix) with ESMTP id 0040A4022B; Thu, 6 Dec 2007 17:56:34 +0100 (CET) Date: Thu, 6 Dec 2007 17:56:08 +0100 From: Bjorn Gronvall To: julien.bellang@free.fr Message-ID: <20071206175608.594685d9@ibook.sics.se> In-Reply-To: <1196953310.47580ede28676@imp.free.fr> References: <1196788555.47558b4bab0ab@imp.free.fr> <1196953310.47580ede28676@imp.free.fr> Organization: SICS.SE X-Mailer: Claws Mail 2.9.1 (GTK+ 2.10.6; i386-portbld-freebsd6.2) Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8bit Cc: freebsd-fs@freebsd.org Subject: Re: FSCK doesn't correct file size when INCORRECT BLOCK COUNT is found X-BeenThere: freebsd-fs@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Filesystems List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 06 Dec 2007 17:29:55 -0000 On Thu, 06 Dec 2007 16:01:50 +0100 julien.bellang@free.fr wrote: Hi Julien, > 1) First some information about the file corrupted : > In my case the Files System has the following characteristics > - the write cache is activated on the hard drive > - the SoftUpdate option is activated > - the FS is mount with the default option noasync Filesystems in general and UFS with soft updates in particular rely on disks providing accurate response to writes. When write caching is enabled the disk will lie and tell the operating system that the write has completed successfully, in reality the data is only cached in disk RAM. When the power disappears the data will be gone forever. In order to avoid this problem you can turn off write caching, this way the software knows if the write completed successfully or not. Alternatively you may power your disks from batteries, multiple power supplies with UPS:es or come up with some other hardware solution. Cheers, /b -- _ _ ,_______________. Bjorn Gronvall (Björn Grönvall) /_______________/| Swedish Institute of Computer Science | || PO Box 1263, S-164 29 Kista, Sweden | Schroedingers || Email: bg@sics.se, Phone +46 -8 633 15 25 | Cat |/ Cellular +46 -70 768 06 35, Fax +46 -8 751 72 30 '---------------'