From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mark Lord Subject: Re: USB-Storage, slow speed with sync option Date: Wed, 14 Sep 2005 17:38:36 -0400 Message-ID: <4328985C.4000207@rtr.ca> References: <43277485.6030802@yahoo.de> <1126690298.4248.44.camel@localhost.localdomain> <4327FB2C.5000207@yahoo.de> <1126694013.4248.49.camel@localhost.localdomain> <4327FEE7.7020707@yahoo.de> <43281B5E.2090702@bouton.name> <1126702271.4248.56.camel@localhost.localdomain> <43284126.8040007@rtr.ca> <432843E5.1060209@bouton.name> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from cpu1185.adsl.bellglobal.com ([207.236.110.166]:25836 "EHLO mail.rtr.ca") by vger.kernel.org with ESMTP id S932774AbVINVii (ORCPT ); Wed, 14 Sep 2005 17:38:38 -0400 In-Reply-To: <432843E5.1060209@bouton.name> Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: Lionel Bouton Cc: Erik Slagter , linux-ide@vger.kernel.org Lionel Bouton wrote: > Mark Lord wrote the following on 14.09.2005 17:26 : >> These flash sticks, along with CF and SD cards, all include >> built-in controllers that do automatic wear-leveling. > > Do they all have such controllers now? Last time I checked, low quality > parts didn't have them and it wasn't easy to verify which ones did. Pretty much all of them use NAND flash, which comes with 1-3% bad blocks from the factory. So the onboard controllers already have to deal with *that* issue, and the same remapping logic is normally extended to allow them to do wear leveling as well. Wear leveling is imperfect, in that they devices can only include sectors *known* by the *device* to be inactive, so as files are written and deleted many sectors are removed from the wear rotation until the next time they are logically rewritten (or until a CFA ERASE command, which Linux never does. Sad.). Cannot say for sure whether 100% of controllers are adequately intelligent, but that kind of control logic is pretty pervasive these days. It would be a very rare device indeed that lacks it. Cheers