From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from risingsoftware01.propagation.net ([66.221.33.65]) by bombadil.infradead.org with esmtps (Exim 4.68 #1 (Red Hat Linux)) id 1Jxykt-0004Ym-VK for linux-mtd@lists.infradead.org; Mon, 19 May 2008 06:21:56 +0000 Received: from c122-107-142-134.eburwd5.vic.optusnet.com.au ([122.107.142.134] helo=noddy.cloud.net.au) by risingsoftware01.propagation.net with esmtpsa (TLS-1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.63) (envelope-from ) id 1Jxykr-0005zH-Jl for linux-mtd@lists.infradead.org; Mon, 19 May 2008 01:21:53 -0500 Received: from hamish by noddy.cloud.net.au with local (Exim 4.69) (envelope-from ) id 1Jxykn-0004Kf-4Q for linux-mtd@lists.infradead.org; Mon, 19 May 2008 16:21:49 +1000 Date: Mon, 19 May 2008 16:21:49 +1000 From: Hamish Moffatt To: linux-mtd@lists.infradead.org Subject: ext2 for read-only file system on UBI Message-ID: <20080519062149.GA16462@cloud.net.au> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , My embedded device has a read-only root file system which is only replaced by writing a whole image (dd, flashcp, ubiupdatevol etc). Using gluebi and mtdblock, I think I can put a traditional block file system (eg ext2) on top of NAND flash. What are the disadvantages of this? (For the read-only application only.) Background: I've got older hardware which uses ext2 on top of compact flash in IDE mode, and new hardware which has replaced the compact flash with NAND. I'd like to share an ext2 image between the two if possible. The read-write file systems use ubifs. I'm only considering this for the read-only volumes. One obvious disadvantage is lack of compression. Are there others? Do I still get the reliability of ubi? ie what does "UBI is not an FTL" mean in practice? thanks, Hamish -- Hamish Moffatt VK3SB