But reading this.....

https://raid.wiki.kernel.org/index.php/RAID_superblock_formats#The_version-1_Superblock_Format

it makes a sound argument for the metadata superblock being at the
beginning of the drive.......in a nutshell the kernel can 'construct'
the md device easier if the metadata is at the beginning....as well as
data resilience issues in the case of a crash.



On 24 May 2015 at 10:46, Mikael Abrahamsson [off-list ref] wrote:

On Sun, 24 May 2015, Another Sillyname wrote:

quoted

I suspect you're correct in that I'll end up with the boot partitions
being in RAID1 and the data in RAID6, however I am seriously
considering having the boot in RAID6 as well...if I can integrate the
mdadm.conf into the initramfs properly I can't see a reason not to do
this?

The initramfs is usually located on the boot partition. A raid1 partition
with a filesystem can be read by the bootloader even if the bootloader
doesn't understand to start the raid first. This is not possible with raid6.

So /boot is usually raid1.

quoted

Had a look at the metadata=0.9 option but reading the info on mdadm
metadata I think I'd prefer to have the metadata at the start of the
drive, also it looks like metadata=1.2 has extra functionality that I
may want to use later.

Look at v1.0 superblock, it has the same functionality but stores the
superblock at the end.


--
Mikael Abrahamsson    email: swmike@swm.pp.se