# Make an existing gmirror bootable



## Pushrod (May 31, 2013)

I had an existing gmirror of two 1 TB disks with data on it, and decided to move that data into a subdirectory, and then make it the new root filesystem. I copied the current root filesystem to it using dump and restore, which worked just fine.

I can use it at the root filesystem, but only by booting off of the old root filesystem, and setting the root device to be the mirror. The issue is clearly between the MBR and loading the kernel.

There is a single, whole-disk partition, and it is the "a" slice, as opposed to "d". It was set up with `fdisk -I`, probably.

It's been about five years since I did anything with boot devices in FreeBSD. Any ideas on how to make the mirror bootable?


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## wblock@ (May 31, 2013)

Make a backup first, then install bootcode in the MBR.  The new Handbook section on gmirror(8) shows how to do that with gpart(8).

Oh, and don't forget to set the partition active.  That section shows that also.


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