From owner-freebsd-hackers@FreeBSD.ORG Sat Aug 20 23:14:15 2005 Return-Path: X-Original-To: freebsd-hackers@freebsd.org Delivered-To: freebsd-hackers@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id A0E1216A41F for ; Sat, 20 Aug 2005 23:14:15 +0000 (GMT) (envelope-from imp@bsdimp.com) Received: from harmony.village.org (vc4-2-0-87.dsl.netrack.net [199.45.160.85]) by mx1.FreeBSD.org (Postfix) with ESMTP id 41F8343D46 for ; Sat, 20 Aug 2005 23:14:15 +0000 (GMT) (envelope-from imp@bsdimp.com) Received: from localhost (localhost.village.org [127.0.0.1]) by harmony.village.org (8.13.3/8.13.3) with ESMTP id j7KNCY5T025174; Sat, 20 Aug 2005 17:12:38 -0600 (MDT) (envelope-from imp@bsdimp.com) Date: Sat, 20 Aug 2005 17:12:38 -0600 (MDT) Message-Id: <20050820.171238.122195775.imp@bsdimp.com> To: hselasky@c2i.net From: "M. Warner Losh" In-Reply-To: <200508201230.37976.hselasky@c2i.net> References: <200508200359.j7K3xoHF015718@ambrisko.com> <20050820031508.A73274@odysseus.silby.com> <200508201230.37976.hselasky@c2i.net> X-Mailer: Mew version 3.3 on Emacs 21.3 / Mule 5.0 (SAKAKI) Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-2.0 (harmony.village.org [127.0.0.1]); Sat, 20 Aug 2005 17:12:38 -0600 (MDT) Cc: freebsd-hackers@freebsd.org Subject: Re: Parking disk drive heads X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 20 Aug 2005 23:14:15 -0000 In message: <200508201230.37976.hselasky@c2i.net> Hans Petter Selasky writes: : On Saturday 20 August 2005 10:18, Mike Silbersack wrote: : > On Fri, 19 Aug 2005, Doug Ambrisko wrote: : > > Flash is nice but it has some issues. Atleast dropping it isn't one! : > > : > > Doug A. : > : > I'd be really happy if I could get a USB flash drive to last more than 8 : > months. Luckily, I started weekly backups after the first failure. That : > helped a lot when the second failure happened. : > : : Flash drives does usually not last more than 10000 writes, per bit, from what : I know. Probably you need some kind of special file-system that moves the : files around as the write quoute gets used up! Eventually the size of the : disk will reach zero, and you have to move the files elsewhere :-) But this : is probably off topic. Actually, 10,000 writes per bit is one or two orders of magnitude too low these days. It was more typical for the Linear Flash PCMCIA cards from 10 years ago. Today, typically flash devices are good for more like 100,000 or 500,000 writes per cell, and all the fobs you'd buy these days have built-in wear averaging. I've tried three times now to wear out a flash by writing an incrementing counter to a single location only to give up after weeks of hammering due to external factors (power failure, network failure, etc). Warner