From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from b.ns.miles-group.at ([95.130.255.144] helo=radon.swed.at) by merlin.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1WCI5p-0003tH-Je for linux-mtd@lists.infradead.org; Sun, 09 Feb 2014 00:17:54 +0000 Message-ID: <52F6C916.2030506@nod.at> Date: Sun, 09 Feb 2014 01:17:26 +0100 From: Richard Weinberger MIME-Version: 1.0 To: Willy Tarreau Subject: Re: [PATCH 1/1] ubi: Introduce block devices for UBI volumes References: <1391027881-8354-1-git-send-email-ezequiel.garcia@free-electrons.com> <1391027881-8354-2-git-send-email-ezequiel.garcia@free-electrons.com> <20140208225149.GA22376@1wt.eu> <52F6B602.3030905@nod.at> <20140208230159.GC22376@1wt.eu> <52F6BA07.60707@nod.at> <20140208231501.GG22376@1wt.eu> <52F6BCCD.5070302@nod.at> <20140208233758.GH22376@1wt.eu> In-Reply-To: <20140208233758.GH22376@1wt.eu> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: Thomas Petazzoni , Mike Frysinger , Artem Bityutskiy , Michael Opdenacker , "linux-mtd@lists.infradead.org" , Ezequiel Garcia , Piergiorgio Beruto , Brian Norris , David Woodhouse List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Am 09.02.2014 00:37, schrieb Willy Tarreau: >>> I gave an example with ext2 for the config. It's a bit excessive to >>> quickly declare "there is simply no use case for $put_your_option_here", >>> it just means that *you* don't have this use case, which I perfectly >>> respect. >> >> The mail with your ext2 use case arrived afterward I've sent that mail. > > No problem. > >> So you are using ext2 as config filesystem because you're facing issues with ubifs? > > No, I've been using ext2 on x86-based hardware and compact flash for > something like 10 years with a great success (easy to mount, easy to > fix, easy to save, easy to occasionally add a backup copy or an extra > data file, etc). I contemplated ubifs on NAND devices as an alternative > when starting to play with ARM-based devices, and lost the reliability > and ability to fix. Switching back to the proven ext2 completely solved > the issues in the end. Ubifs is nice when you need a real read/write FS, > but most small devices do not need wear leveling or any of such nice > features. When you just write 1-10 times a year, other solutions are > fine enough. Using mtdblock directly is not reliable because of bad > blocks which come from time to time. If your FS happens to be located > on one of them, you're screwed. UBI solves such issues and ubiblock > provides a nice interface for this. I even thought about putting the > kernel on top of UBI so that it better resists NAND issues, but some > versions of u-boot do not seem to update it correctly. Thanks a lot for the detailed explanation. > In fact, my feeling is that ubiblock provides the same flexibility > with MTD as you have on new devices with eMMC. You have no wear > levelling, and so what ? You never know if your eMMC does it well > either. I even had a series of compactflash which died after a small > number of writes in the past, so that has existed and will always. > > Also, all these low-level features on top of MTD are used by people > who try to build systems and who are expected to understand a little > bit some of the limits of the solutions they use. It's not the basic > joe user who will install ext4 on top of ubiblock on his NAND by > himself. My experience has shown the opposite. ;-) > This I think it's a bad idea to artificially remove some features > if they're not broken. Your arguments have convinced me, let's keep it and hope the best. Thanks, //richard