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SubjectRe: Linux mdadm superblock question.

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.
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>> 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?


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