From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Woodhouse Subject: Re: Power cut in management Date: Sat, 18 Oct 2008 13:04:53 +0100 Message-ID: <1224331493.6770.1360.camel@macbook.infradead.org> References: <4917.79.37.233.237.1224328849.squirrel@nausicaa2.coritel.it> <20081018114910.GA29345@shareable.org> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20081018114910.GA29345@shareable.org> Sender: linux-embedded-owner@vger.kernel.org List-ID: Content-Type: text/plain; charset="us-ascii" To: Jamie Lokier Cc: marco.stornelli@coritel.it, linux-embedded@vger.kernel.org On Sat, 2008-10-18 at 12:49 +0100, Jamie Lokier wrote: > Can you use a journalling filesystem like ext3, reiserfs, xfs, or even > UBIFS on the card, or does it have to be FAT? With a journalling > filesystem, they vary on the details but basically if you can finish > the current write request in progress, there's no fs-level corruption. Careful. When you use a solid state "disk", you're actually using your file system on top of an underlying "pseudo-filesystem" which makes the flash pretend to be a disk. Your data are at the mercy of that underlying code, which in our past experience always seem to have been implemented by the same crack-smoking hobos they drag in off the street to write PC BIOSes. However good your own journalling file system on _top_ of that 'disk' is, you can still lose everything with a badly timed power-off. If you want to store data on solid state media, my current advice is either to do it on _real_ flash directly with a flash-based file system like JFFS2 or UBIFS, or to pray regularly to the deity of your choice. -- dwmw2