From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail2.shareable.org ([80.68.89.115]) by bombadil.infradead.org with esmtps (Exim 4.68 #1 (Red Hat Linux)) id 1K37Te-0003On-Tz for linux-mtd@lists.infradead.org; Mon, 02 Jun 2008 10:41:23 +0000 Date: Mon, 2 Jun 2008 11:41:06 +0100 From: Jamie Lokier To: =?iso-8859-1?Q?J=F6rn?= Engel Subject: Re: big flash disks? Message-ID: <20080602104106.GC31032@shareable.org> References: <20080601184239.GA11135@shareable.org> <20080602072842.GB19219@logfs.org> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20080602072842.GB19219@logfs.org> Cc: linux-mtd@lists.infradead.org List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Jörn Engel wrote: > Basically they create a log-structured block device. For a while I've > been thinking of doing the same, essentially strip logfs down to a > single file, which gets a block device interface. Removing all the > filesystem complexities (atomic create/unlink/rename, interactions with > vfs and mm, etc.) makes the project a _lot_ simpler. I'm nor surprised > they have a usable product already. > > I decided against it, because I don't believe it to be the best approach > long-term. One of the disadvantages is that block devices have > relatively little knowledge about caching constraints. A filesystem can > easily have gigabytes of dirty data around, where a block device is > expected to return success for every single write in a reasonable > timeframe, usually measures in milliseconds. Won't you get essentially the same by creating a single file on LogFS, and using it for a loopback mount? Sure, it's more complicated under the hood than a stripped-down LogFS, but will it behave and perform similarly? -- Jamie