Bootable RAID10 on 9.0-RELEASE

[Ravi Pokala]

-----Original Message-----
From: Alexander Motin <mav at FreeBSD.org>
Date: Fri, 03 Feb 2012 00:30:12 +0200
To: Ravi Pokala <rp_freebsd at mac.com>
Cc: <freebsd-geom at FreeBSD.org>
Subject: Re: Bootable RAID10 on 9.0-RELEASE

>Hi.
>
> > I expect there must be an easier way.
>
>If your system has one of supported software RAID BIOSes (Intel,
>AMD/Promise, NVIDIA, SiI, JMicron), you may just use geom_raid to boot
>from it's RAID10 volume with no additional magic.

I played around with a VM (with all the IO I was doing, I'm real glad it
was backed by SSDs!) before I had the actual hardware, and managed to get
"close" to what I wanted:

1) Install on a temporary drive.

2) Set up GPT partitions, *including writing the pmbr and gptboot*, on
each of the final drives. It took me a few attempts before I realized I
was creating the partition table but not installing the bootcode.

3) Use `gmirror' to create a mirror of the partition which will hold the /
filesystem, *on all four of the final drives*. That means you will end up
with a quadruplicated /.

4) Use `gmirror' to create mirrors of da0pX and da1pX, and da2pX and da3pX
on the final drives.

5) Use `gstripe' to create stripes across the corresponding mirrors.

6) Create filesystems on the quadruplicated mirror and the stripes.

7) Add the right entries to /boot/loader.conf, update /etc/fstab, etc.

8) Use 'dump | restore' to copy everything from the temporary drive to the
four-way-mirror and the striped-mirrors.

9) Change the boot-order, and make sure you can boot off the four-way
mirror and mount the striped-mirrors.

When I got a chance to play with the actual hardware, I found that it has
an LSI SAS controller which is supported by mfi(4). I ended up setting up
the RAID10 in the pre-boot environment, then just creating GPT partitions
on mfid0 and going from there. *Much* easier (once I dug up the
documentation on LSI's website), works fine, and the interface offered by
`mfiutil' looks pretty reasonable.

Thanks,

rp

>
>-- 
>Alexander Motin
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