From mboxrd@z Thu Jan 1 00:00:00 1970 Subject: Re: JFFS2 losing files on mount From: David Woodhouse To: Ricard Wanderlof In-Reply-To: References: Content-Type: text/plain Date: Thu, 22 Jan 2009 15:03:39 +1100 Message-Id: <1232597019.3921.2.camel@macbook.infradead.org> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Cc: Marco Braga , "linux-mtd@lists.infradead.org" List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Wed, 2009-01-21 at 16:05 +0100, Ricard Wanderlof wrote: > > On Wed, 21 Jan 2009, Marco Braga wrote: > > > I am doing some power failure tests on an ARM7 based device using > > JFFS2 on NAND flash and I am a bit disappointed by the early results. > > ... > > I'd like to hear your experiences. What do you think? > > We use JFFS2 on both an ARM9-platform and on our own CRIS platform. We > never unmount the device in preparation for power down; when someone pulls > the plug, the system just dies. While we do occasionally see warning > messages about incomplete nodes during the next boot-up, we have never > experienced anything as severe as you mention, and we have not lost any > files on the JFFS2 filesystem either. Is this on NAND, or NOR flash? On NAND flash, you do actually have to have non-buggy userspace; if you don't use sync() or fsync() appropriately then there may be data which aren't yet flushed to the flash. On NOR flash, we're a whole lot more tolerant of buggy userspace. Which is what >99% of reports like Marco's turn out to be. Although we're always interested in the possibility that it _does_ turn out to be a real JFFS2 bug... -- David Woodhouse Open Source Technology Centre David.Woodhouse@intel.com Intel Corporation