From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from resqmta-po-09v.sys.comcast.net ([96.114.154.168]:46150 "EHLO resqmta-po-09v.sys.comcast.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752477AbaLHRUM (ORCPT ); Mon, 8 Dec 2014 12:20:12 -0500 Message-ID: <5485DDC7.2080500@pobox.com> Date: Mon, 08 Dec 2014 09:20:07 -0800 From: Robert White MIME-Version: 1.0 To: Konstantin , Phillip Susi , MegaBrutal , linux-btrfs Subject: Re: PROBLEM: #89121 BTRFS mixes up mounted devices with their snapshots References: <547CE175.6060409@web.de> <547E10BA.6000707@ubuntu.com> <5484F198.3070206@web.de> In-Reply-To: <5484F198.3070206@web.de> Content-Type: text/plain; charset=utf-8; format=flowed Sender: linux-btrfs-owner@vger.kernel.org List-ID: On 12/07/2014 04:32 PM, Konstantin wrote: > I know this and I'm using 0.9 on purpose. I need to boot from these > disks so I can't use 1.2 format as the BIOS wouldn't recognize the > partitions. Having an additional non-RAID disk for booting introduces a > single point of failure which contrary to the idea of RAID>0. GRUB2 has raid 1.1 and 1.2 metadata support via the mdraid1x module. LVM is also supported. I don't know if a stack of both is supported. There is, BTW, no such thing as a (commodity) computer without a single point of failure in it somewhere. I've watched government contracts chase this demon for decades. Be it disk, controller, network card, bus chip, cpu or stick-of-ram you've got a single point of failure somewhere. Actually you likely have several such points of potential failure. For instance, are you _sure_ your BIOS is going to check the second drive if it gets read failure after starting in on your first drive? Chances are it won't because that four-hundred bytes-or-so boot loader on that first disk has no way to branch back into the bios. You can waste a lot of your life chasing that ghost and you'll still discover you've missed it and have to whip out your backup boot media. It may well be worth having a second copy of /boot around, but make sure you stay out of bandersnatch territory when designing your system. "The more you over-think the plumbing, the easier it is to stop up the pipes."