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 1NwfqS-0001N1-H9 for garchives@archives.gentoo.org; Tue, 30 Mar 2010 18:07:24 +0000 Received: from pigeon.gentoo.org (localhost [127.0.0.1]) by pigeon.gentoo.org (Postfix) with SMTP id 28FBCE0CB9 for ; Tue, 30 Mar 2010 18:07:20 +0000 (UTC) Received: from hrndva-omtalb.mail.rr.com (hrndva-omtalb.mail.rr.com [71.74.56.124]) by pigeon.gentoo.org (Postfix) with ESMTP id 3EA68E0913 for ; Tue, 30 Mar 2010 17:58:03 +0000 (UTC) X-Authority-Analysis: v=1.0 c=1 a=NgErzj9CHnEA:10 a=8nJEP1OIZ-IA:10 a=JmiZSqO8Pn5pcunSz20A:9 a=qo1EfFU1jC9plA9acY8A:7 a=MJiO5iYGVzhawgiR_Hs26j2qIzUA:4 a=wPNLvfGTeEIA:10 a=o9SDJomN1uUPD-t9:21 a=QunXWUgSDPs2R6bY:21 X-Cloudmark-Score: 0 X-Originating-IP: 71.40.157.251 Received: from [71.40.157.251] ([71.40.157.251:54526] helo=[192.168.2.37]) by hrndva-oedge02.mail.rr.com (envelope-from ) (ecelerity 2.2.2.39 r()) with ESMTP id 22/CF-20831-AAB32BB4; Tue, 30 Mar 2010 17:58:02 +0000 Message-ID: <4BB23EDE.3090407@tampabay.rr.com> Date: Tue, 30 Mar 2010 14:11:42 -0400 From: wireless User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.8.1.23) Gecko/20100301 SeaMonkey/1.1.18 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 To: gentoo-embedded@lists.gentoo.org Subject: Re: [gentoo-embedded] file system question References: <20100329184215.539920eb@osage.osagesoftware.com> <4BB20C81.5010102@wildgooses.com> In-Reply-To: <4BB20C81.5010102@wildgooses.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit X-Archives-Salt: 0aa77178-f1e6-4d6a-b6a9-ce953b59e2f6 X-Archives-Hash: 40cfe036c32663b619812c45b53d5341 Ed W wrote: > In addition to what everyone else has already noted you really need to > state your tradeoff between lifetime of the flash cards and minimising > the risk of loosing data. Wow, this sounds like a PC programmer's statement and not how an embedded designer would solve the problem. Granted the poster has not provided and adequate 'specification' so my point of view may or may not be precisely applicable. >From what I have gleaned, the developer should first look at a low power system, with battery backup. If it is an embedded system designed to run as such, a simple 9V battery should provide years/decades of reliability to 5 nines of uptime or more..... This robust research and design approach will solve power cycling-data loss problems.... Depending on the details of the data collection sensors and hardware, either redesign as low power, or put them on a separate power supply. If that, (relatively) hi power supply is intermittent, you only loose data for those data collection intervals. You CPU/storage module never looses power. Some very fast AD devices are power hogs. Other (slower) AD devices are very power efficient, especially if they 'sleep' (low or off power mode) when not actively needed. This is controlled I could go on and on, but just purchasing a SBC and trying to turn it into a robust product, is rarely successful in my experience. USE and SBC of the shelf to get your coders coding, and get a hardware designer to look at the specification, and design a low power, minimized design that has what you need and nothing else. Then when you ramp up quantity, you'll actually make a profit as your competition lowers their price, you can still compete. It's impossible, in my experience, to use off the shelf SBC and be competitive for very long. Your competition will under cut you every time.... hth, James