From owner-freebsd-questions@FreeBSD.ORG Tue Jun 23 20:14:36 2009 Return-Path: Delivered-To: FreeBSD-Questions@FreeBSD.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 53CEB106568B for ; Tue, 23 Jun 2009 20:14:36 +0000 (UTC) (envelope-from dkelly@Grumpy.DynDNS.org) Received: from smtp.knology.net (smtp.knology.net [24.214.63.101]) by mx1.freebsd.org (Postfix) with ESMTP id DD79A8FC0C for ; Tue, 23 Jun 2009 20:14:35 +0000 (UTC) (envelope-from dkelly@Grumpy.DynDNS.org) Received: (qmail 29633 invoked by uid 0); 23 Jun 2009 20:14:32 -0000 Received: from unknown (HELO Grumpy.DynDNS.org) (24.42.224.110) by smtp2.knology.net with SMTP; 23 Jun 2009 20:14:32 -0000 Received: by Grumpy.DynDNS.org (Postfix, from userid 928) id C4E0F2841F; Tue, 23 Jun 2009 15:14:31 -0500 (CDT) Date: Tue, 23 Jun 2009 15:14:31 -0500 From: David Kelly To: FreeBSD-Questions@FreeBSD.org Message-ID: <20090623201431.GA43645@Grumpy.DynDNS.org> References: <20090622230729.GA20167@thought.org> <20090623170739.GA33220@slackbox.xs4all.nl> <20090623182225.GC33220@slackbox.xs4all.nl> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.4.2.3i Cc: Subject: Re: you're not going to believe this. X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list Reply-To: FreeBSD-Questions@FreeBSD.org List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 23 Jun 2009 20:14:36 -0000 On Tue, Jun 23, 2009 at 09:46:01PM +0200, Wojciech Puchar wrote: > >>and lifetime. > > > >Even a flash filesystem will have to do wear levelling. > > yes - but it don't have to copy blocks that are free. with disk > emulation - it doesn't know anything about filesystem and don't know > what blocks are free. If it is swapping from heavily used blocks to lightly used blocks then "so what" if there is an "unnecessary" read/write? Perhaps its harder to determine if unused than to simply move the data. I seem to recall something like this in comments in the FreeBSD virtual memory manager in 6.0-RELEASE. Don't want to leave the old data laying around for security reasons so even if the blocks are unused the formerly heavily used blocks need to be scrubbed. As I originally said to Gary Kline, "Don't let someone scare you away from the 99.8% solution waiting on the 99.9% solution." -- David Kelly N4HHE, dkelly@HiWAAY.net ======================================================================== Whom computers would destroy, they must first drive mad.