From mboxrd@z Thu Jan 1 00:00:00 1970 From: Justin Piszcz Subject: Re: Linux mdadm superblock question. Date: Sat, 13 Feb 2010 15:07:51 -0500 (EST) Message-ID: References: <4877c76c1002111752h23e14f7aibe58a89181e6f493@mail.gmail.com> <4B77044B.1020609@zytor.com> Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed Return-path: In-Reply-To: <4B77044B.1020609@zytor.com> Sender: linux-kernel-owner@vger.kernel.org To: "H. Peter Anvin" Cc: Michael Evans , linux-raid@vger.kernel.org, linux-kernel@vger.kernel.org List-Id: linux-raid.ids On Sat, 13 Feb 2010, H. Peter Anvin wrote: > On 02/11/2010 05:52 PM, Michael Evans wrote: >> On Thu, Feb 11, 2010 at 3:00 PM, Justin Piszcz wrote: >>> Hi, >>> >>> I may be converting a host to ext4 and was curious, is 0.90 still the only >>> superblock version for mdadm/raid-1 that you can boot from without having to >>> create an initrd/etc? >>> >>> Are there any benefits to using a superblock > 0.90 for a raid-1 boot volume >>> < 2TB? >>> >>> Justin. >>> -- >>> To unsubscribe from this list: send the line "unsubscribe linux-raid" in >>> the body of a message to majordomo@vger.kernel.org >>> More majordomo info at http://vger.kernel.org/majordomo-info.html >>> >> >> You need the superblock at the end of the partition: If you read the >> manual that is clearly either version 0.90 OR 1.0 (NOT 1.1 and also >> NOT 1.2; those use the same superblock layout but different >> locations). > > 0.9 has the *serious* problem that it is hard to distinguish a whole-volume > > However, apparently mdadm recently switched to a 1.1 default. I > strongly urge Neil to change that to either 1.0 and 1.2, as I have > started to get complaints from users that they have made RAID volumes > with newer mdadm which apparently default to 1.1, and then want to boot > from them (without playing MBR games like Grub does.) I have to tell > them that they have to regenerate their disks -- the superblock occupies > the boot sector and there is nothing I can do about it. It's the same > pathology XFS has. > > -hpa > My original question was does the newer superblock do anything special or offer new features *BESIDES* the quicker resync? Justin.