From owner-freebsd-arm@freebsd.org Tue Mar 22 02:38:14 2016 Return-Path: Delivered-To: freebsd-arm@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id 8FCC5AD8FEB for ; Tue, 22 Mar 2016 02:38:14 +0000 (UTC) (envelope-from wlosh@bsdimp.com) Received: from mail-io0-x232.google.com (mail-io0-x232.google.com [IPv6:2607:f8b0:4001:c06::232]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority G2" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 5C07C7DC for ; Tue, 22 Mar 2016 02:38:14 +0000 (UTC) (envelope-from wlosh@bsdimp.com) Received: by mail-io0-x232.google.com with SMTP id 124so78808175iov.3 for ; Mon, 21 Mar 2016 19:38:14 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bsdimp-com.20150623.gappssmtp.com; s=20150623; h=mime-version:sender:in-reply-to:references:date:message-id:subject :from:to:cc; bh=dmXXigBnwN3vwnSbiJIkvWXdomxI64mkHdnmwO4+Ai0=; b=TZY8tHZhJ5ZAU56N77pZFx0sIO+XrNGftKlwdMVtUEaoz+4Glr3+/n0BxEhxYicEUy O68wH/GlS7UsT1YepH9Zn0YSHOGPI9Yg2rFQqAdvHM0jgj9gps3T/ZInxB7GOGYvnTtl EcrfN2ryNrCafR3Djryr2rIzmoto90k/igs+wMFkIG7WqYbxJ0uVl6wKJKinoDIbnBuq JOj073mbGWuOU/eB72uZiYbAypWUmWpWiCPAcCpaH+YIQg1f/5DYm+u48MPstlEo26Wn z7eF6EAGc2tjE0PFcFH0hogtl8AU6+DO2y9gwilFMm4xQxdepQUh+QnV+S7EPVjkT3yq OsVg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:mime-version:sender:in-reply-to:references:date :message-id:subject:from:to:cc; bh=dmXXigBnwN3vwnSbiJIkvWXdomxI64mkHdnmwO4+Ai0=; b=EqQfYoJ8GZOU+Nk5q/Rub686NRYMqkLPs9VWQnlnF6tx1/e6I3RG9/030pdgwKE1yH wkSTAn6wQvvIfA3bY6zpopcL1lykrsWPaXM8i8/TEoLRbfbKpBIP0F46YmpdJRqREWD2 q3xjgtAcvzXgsEIfkhUR1FgKcQqWWpYIhXBp4f+v91PrkM3VIEXe0k9bILCl8pVoL4LH xjLI56QzAJY3BULqfdWvfPUy4tgHPDNHRxOBF+JnNGg9rGH7Sc8X/kLZoaNl5Yo1qAlH CiICwtTfEXk/FbYMVpJWHj6XKf31EoG3BdzLpQ3TFbMPU3jKIRceuyZcmnemE1Fg3ZzW ugRg== X-Gm-Message-State: AD7BkJJu2DeYNrQQXvcASE53H8t7mkXQ8S05couBJLUci0UmLFqks5bDbOUoL0hOsXwfw00qCHXmbDsdHMaonQ== MIME-Version: 1.0 X-Received: by 10.107.155.206 with SMTP id d197mr29657340ioe.135.1458614293739; Mon, 21 Mar 2016 19:38:13 -0700 (PDT) Sender: wlosh@bsdimp.com Received: by 10.36.65.230 with HTTP; Mon, 21 Mar 2016 19:38:13 -0700 (PDT) X-Originating-IP: [2607:fb90:125:5e44:0:1b:257b:6d01] Received: by 10.36.65.230 with HTTP; Mon, 21 Mar 2016 19:38:13 -0700 (PDT) In-Reply-To: <1973487B-0AA7-468D-A9CC-319FBE2122F0@netgate.com> References: <20160321175952.GA83908@www.zefox.net> <1458586884.68920.96.camel@freebsd.org> <20160321221153.GB83908@www.zefox.net> <1458600070.68920.107.camel@freebsd.org> <1973487B-0AA7-468D-A9CC-319FBE2122F0@netgate.com> Date: Mon, 21 Mar 2016 20:38:13 -0600 X-Google-Sender-Auth: 413POKoLou--gC0IE4tya8ime_w Message-ID: Subject: Re: Effect of partitioning on wear-leveling From: Warner Losh To: Jim Thompson Cc: Ian Lepore , freebsd-arm@freebsd.org Content-Type: text/plain; charset=UTF-8 X-Content-Filtered-By: Mailman/MimeDel 2.1.21 X-BeenThere: freebsd-arm@freebsd.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: "Porting FreeBSD to ARM processors." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 22 Mar 2016 02:38:14 -0000 On Mar 21, 2016 8:15 PM, "Jim Thompson" wrote: > > > > On Mar 21, 2016, at 4:41 PM, Ian Lepore wrote: > > > > Also, it's been my experience that it's impossible to "wear out" an > > sdcard. I once ran a program that just wrote random data continuously > > at full speed to a 512MB card for several months nonstop. No noticible > > effect on the card. I actually still use that card today (in one of > > our older products whose filesystem image only needs about 40MB). > > Now try random power fails while writing. It won't last through 1000 of them. (eMMC is way better One thing that people forget is that the underlying blocks that are written are completely independent of what lba is used to write it. So the notion that you have blocks normally part of /var or /tmp no longer makes sense. Between writing blocks in different order and garbage collection, modern SD cards do a good job of wear averaging. How much you've written to the drive in total drives wear out these days. Warner