What's the best way to destroy a geom mirror?

Yuri Pankov yuri.pankov at gmail.com
Thu Mar 5 23:29:32 PST 2009

On Thu, Mar 05, 2009 at 09:35:31AM -0800, Peter Steele wrote:
> I've created a USB boot disk that is used to clone itself onto the systems hard drives, setting up mirrored file systems in the process. The main difficulty I'm having is reimaging a system with an existing OS whose drives are already configured in a mirror. I want of course to destroy the mirror and create a complete new one, but I can't find the right process to accomplish this reliably. I am doing the following: 
> # Cycle through each /dev/adNN drive and clean it. This has to be 
> # done before the geom_mirror driver is loaded. 
> disks=(`ls /dev/ad* | grep -v "s" | sed -e "s|/dev/||" -e "s|ad||" | sort -g`) 
> for ((i = 0 ; i < ${#disks[@]} ; i++)); do 
> disk=ad${disks[i]} 
> dd if=/dev/zero of=/dev/${disk} bs=512 count=79 
> done 
> # Partition the drives as needed 
> ... 
> # Create the mirror, starting with the first drive in the list 
> gmdisk=ad${disks[0]} 
> gmirror load 
> gmirror label -v -n -b round-robin gm0 ${gmdisk}s1 
> This is where the problem occurs. If there was already a mirrored file system previously active on the system being reimaged, the label operation complains that it can't store the metadata on the indicated drive: 
> gmirror: Can't store metadata on ad4s1: Operation not permitted. 
> If I make sure the existing mirrors are torn down first by iterating through the drives and doing a "remove" operation, this can solve the problem, but in some cases the mirror is in a suspect state and I've seen the "gmirror load" command hang idefiinitely. So I don't want to do a load command before I destroy the old mirrors, but I can't seem to find a way to reliably destroy the old mirrors. Can anyone suggest a way to do this? 

Have you tried using 'clear' keyword?


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