From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from pigeon.gentoo.org ([208.92.234.80] helo=lists.gentoo.org) by finch.gentoo.org with esmtp (Exim 4.60) (envelope-from ) id 1Nwweb-0004DS-G6 for garchives@archives.gentoo.org; Wed, 31 Mar 2010 12:04:13 +0000 Received: from pigeon.gentoo.org (localhost [127.0.0.1]) by pigeon.gentoo.org (Postfix) with SMTP id 1F033E0CA2 for ; Wed, 31 Mar 2010 12:04:13 +0000 (UTC) Received: from mail.osagesoftware.com (osagesoftware.com [216.144.204.42]) by pigeon.gentoo.org (Postfix) with ESMTP id B060EE0B26 for ; Wed, 31 Mar 2010 11:30:47 +0000 (UTC) Received: from osage.osagesoftware.com (osage.osagesoftware.com [192.168.1.10]) by mail.osagesoftware.com (Postfix) with ESMTP id 247347BC8B for ; Wed, 31 Mar 2010 07:30:47 -0400 (EDT) Date: Wed, 31 Mar 2010 07:30:47 -0400 From: David Relson To: gentoo-embedded@lists.gentoo.org Subject: Re: [gentoo-embedded] file system question Message-ID: <20100331073047.19c76dc0@osage.osagesoftware.com> In-Reply-To: <20100331112649.7365bb19@sth491dt.servo.net> References: <20100329184215.539920eb@osage.osagesoftware.com> <20100331112649.7365bb19@sth491dt.servo.net> Organization: Osage Software Systems, Inc. X-Mailer: Claws Mail 3.7.5 (GTK+ 2.18.7; x86_64-pc-linux-gnu) Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-Id: Gentoo Linux mail X-BeenThere: gentoo-embedded@lists.gentoo.org Reply-to: gentoo-embedded@lists.gentoo.org Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable X-Archives-Salt: a6d0ad9b-0014-4bd5-8c05-2c0eef9da89e X-Archives-Hash: abb71b837168b7b62e4d21b2bb604dee On Wed, 31 Mar 2010 11:26:49 +0200 Neboj=C5=A1a =C4=86osi=C4=87 wrote: > > G'day, > >=20 > > I'm porting the software for an embedded medical device from DOS to > > Linux and am wondering which file systems are appropriate and which > > are not. The device's mass storage is a Disk-on-Module solid state > > flash drive. Data is presently written at approx 100 bytes every > > 30 seconds but that might change to 100 bytes every second. The > > device has a watchdog (recently activated) and during today's > > session it was triggered and wiped out my file system. > >=20 > > Anybody have recommendations on which file system to use and the > > appropriate settings? > >=20 > > Anybody have suggested readings so I can educate myself? > >=20 > > Thank you. > >=20 > > David > >=20 > After having problems with EMC and usb storage, I finally fixed the > problem with following solution: > - data storage, in my case usb stick, has at least 2 partitions > - second partition is without file system. It is divided in a number > of slots, each large enough to store all of my data > - all work is performed on data stored on ram disk > - periodically (triggered by time and/or data change), I compress ram > disk and dump it in a next slot on unformatted partition > I have a small battery, which I use to do one final dump at shutdown > time. > On startup, I go through all of the slots in second partition, > searching for latest uncorrupt data, and use this to populate ram > disk. If you can live with some data loss, you don't even need > battery backup. No matter wear leveling implementation on your > storage, this solution works optimally. > It works even on your directly accessible flash storage. > Since there is no real file system on partition, there is no need for > it's recovery - besides searching for latest and greatest set of data > on startup > And it is implemented as a ash script, using tar and gzip, so your > data is actually better verified than on normal file system (the > usual one do not actually checksum data. I don't consider jffs2 to be > "the usual filesystem":) > Neboj=C5=A1a Wow! That's a robust solution!