From mboxrd@z Thu Jan 1 00:00:00 1970 From: Michal Soltys Subject: Re: Using the new bad-block-log in md for Linux 3.1 Date: Thu, 28 Jul 2011 14:53:36 +0200 Message-ID: <4E315BD0.7040400@ziu.info> References: <20110727141652.7511fc51@notabene.brown> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20110727141652.7511fc51@notabene.brown> Sender: linux-raid-owner@vger.kernel.org To: NeilBrown Cc: linux-raid@vger.kernel.org List-Id: linux-raid.ids W dniu 27.07.2011 06:16, NeilBrown pisze: > > If you create an array with this mdadm it will add a bad block log - you > cannot turn it off (it is only 4K long so why would you want to). Then as > errors occur they will cause the faulty block to be added to the log rather > than the device to be remove from the array. I was wondering, 4KiB is "just" 512 entries assuming these are only 64bit sector addresses - it's possible to imagine a failing drive with lots of not reloctable (for whatever reason) adjacent sectors, that could fill up the log relatively quickly (mentioned 512 entries ~ 256KiB worth of data on 512b drives, just a few chunks before the drive is kicked out). Though - how realistic such scenario is with modern drives, is hard for me to judge. Still - are there any plans to make that 4KiB size not hardcoded, also perhaps along with customizable offset to the 1st chunk ? Something of analogous functionality to lvm's options such as: --metadatasize --dataalignment --dataalignmentoffset (though again, hard to judge if there's any practical use for those aside exotic scenarios)