From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S964925AbWGHSAH (ORCPT ); Sat, 8 Jul 2006 14:00:07 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S964927AbWGHSAH (ORCPT ); Sat, 8 Jul 2006 14:00:07 -0400 Received: from mail.tmr.com ([64.65.253.246]:59872 "EHLO pixels.tmr.com") by vger.kernel.org with ESMTP id S964925AbWGHSAF (ORCPT ); Sat, 8 Jul 2006 14:00:05 -0400 Message-ID: <44AFF332.6040505@tmr.com> Date: Sat, 08 Jul 2006 14:02:26 -0400 From: Bill Davidsen User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.8.0.4) Gecko/20060516 SeaMonkey/1.0.2 MIME-Version: 1.0 To: Avi Kivity CC: Helge Hafting , Neil Brown , Alan Cox , Arjan van de Ven , Tomasz Torcz , Thomas Glanzmann , "Theodore Ts'o" , LKML Subject: Re: ext4 features (checksums) References: <44ABAA0E.4000907@tmr.com> <44ABAC20.5090902@argo.co.il> In-Reply-To: <44ABAC20.5090902@argo.co.il> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Avi Kivity wrote: > Bill Davidsen wrote: >> >> >> > Not syncing unused area is possible, if there was a way for raid resync >> > to ask the fs what blocks are not in use. I.e. get the >> > free block list in disk block order. Then raid resync could skip >> those. >> > >> Current RAID code supports having a bitmap of dirty stripes, and can >> just sync those during recovery. I'm sure Neil could explain it better, >> but this is available without worrying about fs type. Now. Today. >> > > This is only when the you reconstruct a disk that was once part of the > RAID. If you are adding a brand new disk, all stripes are dirty. I will leave Neil to explain this to you, it appears to be a totally different case for reconfiguration, but I don't pretend to understand the code well enough to clarify it. > > This happens in two scenarios: an unclean RAID shutdown, and when you > have a remote mirror which can be disconnected by network problems. > > If the RAID is integrated in the filesystem (or into an object storage > system), you can handle the new disk case too. > I'm not sure that building the RAID into the filesystem is ever a good idea, it certainly seems likely to either prevent certain RAID devices from being used, or make them perform suboptimally. There are times when being able to move a filesystem to a new device is REALLY useful, and byte copy is more practical than file by file copy. -- Bill Davidsen Obscure bug of 2004: BASH BUFFER OVERFLOW - if bash is being run by a normal user and is setuid root, with the "vi" line edit mode selected, and the character set is "big5," an off-by-one errors occurs during wildcard (glob) expansion.