Forget any on-board pseudo-hardware RAID. Assuming you have the 2nd disk up and 
connected and that your installation is default, mirroring the Osol boot/root 
disk is easy:

# prtvtoc /dev/rdsk/<rootdev>s2 | fmthard -s - /dev/rdsk/<mirrordev>
# zpool attach rpool <rootdev>s0 <mirrordev>s0
# installgrub -m /boot/grub/stage1 /boot/grub/stage2 /dev/rdsk/<mirrordev>s0

Where <mirrordev> (cXdYwhatever) is the same size or larger than <rootdev> and 
could be a USB drive or whatever, but note performance limits. The first line 
copies the partition/slice layout. The second attaches the mirrored slice 0 and 
starts the resilver. The third makes the mirrored disk bootable and has to be 
repeated manually every time there's a GRUB change. Note that in case of 
failure I usually prefer to boot from the install CD (note you'll need the 
current build if you've upgraded the rpool's ZFS version) and do the repair 
from there rather than boot from the mirror incase something other than the 
disk is the problem. If the drives are hot-swappable you can even replace the 
boot disk on a running system and repeat the 1st and 3rd lines above going the 
other way and then doing the "zpool replace"! You might want to practice and 
document this before deployment into production... :-)

You have two options when it comes to s1 for swap: you can either mirror that 
too, or you can just add it as a second swap device as the swap handler is 
pretty robust. A detailed explanation of the trade-offs there I'll leave to 
someone better qualified to explain. :-)

(I know of one individual who has their rpool 2nd mirrored to a 2.5" USB 
powered drive in a fire/flood proof box on the end of a long cable!)

Having had my bacon saved by this with a root disk failure on my home file 
server: I love ZFS! 

Maybe installing Osol to a mirrored pair should be an enhancement request?

 James
-----Original Message-----
From: gm_sjo <[EMAIL PROTECTED]>
Sent: Tuesday, 09 Sep 2008 1:36
To: [email protected]
Subject: Re: [storage-discuss] Is OpenSolaris+iSCSI right for me?

2008/9/9 Andrew M. Hettinger:
> Yes, I am using this board for iSCSI servers now. I have a mirrored drive
> for booting,

Andrew, thanks! I am seriously considering this board now (gotta love
Intel server boards!)

How are you doing the mirror for the o/s? I am wondering if I can use
the onboard SATA raid features on the motherboard you suggest but I
have a feeling that opensolaris may not support that and only display
the individual drives?
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