Adding software RAID to installed system

[Fabian Peters]

Hi Andrew,

Am 06.02.2007 um 19:59 schrieb Andrew Oliver:

> On Feb 6, 2007, at 7:39 AM, Fabian Peters wrote:
>
>> Hi folks,
>>
>> Has anybody successfully created a RAID1 without erasing the  
>> existing boot disk (possibly even w/o rebooting?) on OS X Server  
>> 10.4? Apple's "Getting Started" guide states it's ok:
>>
>> "If the target disk has a single partition and the second physical  
>> drive has a single partition and no data, you can set up RAID  
>> mirroring after installation."
>>
>> Which I figure is what I'd like to do but I feel the wording is a  
>> bit vague. Of course in any case the usual caveats to back up  
>> beforehand do apply...
>>
>> Thanks for your insights
>
> It is possible to do. You may need to reboot, and you can't do it  
> through the GUI.
>
> Assuming your two drives are disk0 and disk1 (use diskutil to  
> verify), and disk0 is your current boot drive
>
> 1) diskutil enableRAID mirror disk0
> This will create a degraded mirror RAID, disk2, consisting of the  
> boot drive (disk0) and nothing else.
>
> 2) diskutil repairMirror disk2 disk1
> This adds disk1 to the existing RAID disk2
>
> 3) Wait (use diskutil checkRAID to check progress)
>
> I've done this many times, and it's worked most of the time.  
> Sometimes, though, the repairMirror fails. That's usually been  
> fixed by booting from DVD and running repairMirror again - in other  
> words there's a higher success rate when you do this on a non-live  
> drive, but I haven't worked out the exact conditions that cause it  
> to fail.

thanks a lot, that's what I was looking for! AFAIR this resembles the  
way it worked with atacontrol under FreeBSD.  I'll keep a clone of  
the boot drive handy in case anything goes wrong.

cheers

Fabian