Date: Tue, 23 Jun 2009 15:14:31 -0500 From: David Kelly <dkelly@hiwaay.net> To: FreeBSD-Questions@FreeBSD.org Subject: Re: you're not going to believe this. Message-ID: <20090623201431.GA43645@Grumpy.DynDNS.org> In-Reply-To: <alpine.BSF.2.00.0906232145290.59407@wojtek.tensor.gdynia.pl> References: <20090622230729.GA20167@thought.org> <alpine.BSF.2.00.0906230929470.55064@wojtek.tensor.gdynia.pl> <20090623170739.GA33220@slackbox.xs4all.nl> <alpine.BSF.2.00.0906231922250.58723@wojtek.tensor.gdynia.pl> <20090623182225.GC33220@slackbox.xs4all.nl> <alpine.BSF.2.00.0906232145290.59407@wojtek.tensor.gdynia.pl>
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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.
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