[gentoo-user] RAID 1 on /boot

[Facundo Curti]

Hi all. I'm new in the list, this is my third message :)
First at all, I need to say sorry if my english is not perfect. I speak
spanish. I post here because gentoo-user-es it's middle dead, and it's a
great chance to practice my english :) Now, the problem.

I'm going to get a new PC with a disc SSD 120GB and another HDD of 1TB. But
in a coming future, I want to add 2 or more disks SSD.

Mi idea now, is:

    Disk HHD: /dev/sda
/dev/sda1 26GB
/dev/sda2 90GB
/dev/sda3 904GB

    Disk SSD: /dev/sdb
/dev/sdb1 26GB
/dev/sdb2 90GB
/dev/sdb3 4GB

And use /dev/sdb3 as swap. (I will add more with another SSD in future)
/dev/sda3 mounted in /home/user/data (to save data unused)

And a RAID 1 with:
md0: sda1+sdb1    /
md1: sda2+sdb2    /home

(sda1 and sda2 will be made with the flag: write-mostly. This is useful for
disks slower).
In a future, I'm going to add more SSD's on this RAID. My idea is the
fastest I/O.

Now. My problem/question is:
Following the gentoo's
doc<http://www.gentoo.org/doc/es/gentoo-x86+raid+lvm2-quickinstall.xml>,
it says I need to put the flag --metadata=0.9 on the RAID. My question is
¿This will make get off the performance?.

I only found this
document<https://raid.wiki.kernel.org/index.php/RAID_superblock_formats#The_version-0.90_Superblock_Format>.
This says the difference, but nothing about performance and
advantages/disadvantages.

Another question is, ¿GRUB2 still unsupporting metadata 1.2?

In case that metadata get off performance, and GRUB2 doesn't support this.
¿Anyone knows how can I fix this to use metadata 1.2?

I don't partitioned more, because I saw this unnecessary. I just need to
separate /home in case I need to format the system. But if I need to
separate /boot to make it work, I don't have problems doing that.

But of course, /boot also as RAID...

¿Somebody have any ideas to make it work?

Thank you all. Bytes! ;)