From mboxrd@z Thu Jan 1 00:00:00 1970 From: Michael Evans Subject: Re: Linux mdadm superblock question. Date: Sat, 13 Feb 2010 13:07:22 -0800 Message-ID: <4877c76c1002131307i61a3c985w8db8c10623a693c8@mail.gmail.com> References: <4877c76c1002111752h23e14f7aibe58a89181e6f493@mail.gmail.com> <4B77044B.1020609@zytor.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: Sender: linux-raid-owner@vger.kernel.org To: david@lang.hm Cc: Justin Piszcz , "H. Peter Anvin" , linux-raid@vger.kernel.org, linux-kernel@vger.kernel.org List-Id: linux-raid.ids On Sat, Feb 13, 2010 at 12:49 PM, wrote: > On Sat, 13 Feb 2010, Justin Piszcz wrote: > >> 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 withou= t >>>>> 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-r= aid" >>>>> in >>>>> the body of a message to majordomo@vger.kernel.org >>>>> More majordomo info at =A0http://vger.kernel.org/majordomo-info.h= tml >>>>> >>>> >>>> You need the superblock at the end of the partition: =A0If you rea= d the >>>> manual that is clearly either version 0.90 OR 1.0 (NOT 1.1 and als= o >>>> 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. =A0I >>> 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 volum= es >>> with newer mdadm which apparently default to 1.1, and then want to = boot >>> from them (without playing MBR games like Grub does.) =A0I have to = tell >>> them that they have to regenerate their disks -- the superblock occ= upies >>> the boot sector and there is nothing I can do about it. =A0It's the= same >>> pathology XFS has. >>> >>> =A0 =A0 =A0 =A0-hpa >>> >> >> My original question was does the newer superblock do anything speci= al or >> offer new features *BESIDES* the quicker resync? > > the older superblocks have limits on the number of devices that can b= e part > of the raid set. > > David Lang > The 1.1 and 1.2 formats ALSO play more nicely with stacking partition contents. LVM, filesystems, and partition info all begin at the start of a block device; putting the md labels there too makes it obvious what order to unpack the structures in. -- To unsubscribe from this list: send the line "unsubscribe linux-raid" i= n the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html