Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261528AbVA2Szd (ORCPT ); Sat, 29 Jan 2005 13:55:33 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261530AbVA2Szd (ORCPT ); Sat, 29 Jan 2005 13:55:33 -0500 Received: from gprs213-58.eurotel.cz ([160.218.213.58]:27520 "EHLO amd.ucw.cz") by vger.kernel.org with ESMTP id S261528AbVA2Sz2 (ORCPT ); Sat, 29 Jan 2005 13:55:28 -0500 Date: Sat, 29 Jan 2005 19:55:15 +0100 From: Pavel Machek To: Andi Kleen Cc: linux-kernel@vger.kernel.org Subject: Re: critical bugs in md raid5 and ATA disk failure/recovery modes Message-ID: <20050129185515.GA2146@elf.ucw.cz> References: <20050127035906.GA7025@schmorp.de> <20050127063131.GA29574@schmorp.de> <20050127095102.GA88779@muc.de> <20050127163323.GA7474@schmorp.de> <20050129183511.GA2055@elf.ucw.cz> <20050129183731.GA40659@muc.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20050129183731.GA40659@muc.de> X-Warning: Reading this can be dangerous to your mental health. User-Agent: Mutt/1.5.6+20040907i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1330 Lines: 31 Hi! > > Well, you could set stripe size to 512B; that way, RAID-5 would be > > *very* slow, but it should have same characteristics as normal disc > > w.r.t. crash. Unrelated data would not be lost, and you'd either get > > old data or new data... > > When you lose a disk during recovery you can still lose > unrelated data (any "sibling" in a stripe set because its parity > information is incomplete). RAID-1 doesn't have this problem though. You are right, I'd have to do soething very special... Like if I know it is 4K filesystem, raid-5 from 5 disks could do the trick. Like Disk1 Disk2 Disk3 Disk4 Disk5 bytes0-511 512-1023 1024-1535 1536-2048 parity .... ....no, even that does not work. You could add single bit for each 4K saying "this stripe is being written" (with barriers etc) and return read errors if bit is set might actually do the trick, but that's no longer raid-5... (Can ext3 handle error in journal?) Pavel -- People were complaining that M$ turns users into beta-testers... ...jr ghea gurz vagb qrirybcref, naq gurl frrz gb yvxr vg gung jnl! - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/