Crashed gmirror, single disk marked SYNC and wont boot...

Johan Ström johan at
Fri Aug 24 02:03:58 PDT 2007

On Aug 21, 2007, at 17:53 , Johan Ström wrote:

> On Aug 21, 2007, at 16:31 , Pawel Jakub Dawidek wrote:
>> All in all, your partition table seems to be gone. If you created  
>> it on
>> gmirror before (gm0s1) you may still have the same partition table on
>> the other half of the mirror. You can try to move it to ad6 with
>> bsdlabel and verify if you can see file system inside partitions.
> Okay, tried that now.. Saved ad0s1 label, reloaded it onto ad6s1..  
> Now I got same partition table on ad6s1 as on ad0s1...
> Trying to mount any though gives me incorrect super block... fsck  
> cannot find any superblocks either..
> So.. What to do now then? Just for get ad6 and start from scratch  
> from ad2? (as i said, the data isnt very old realy)...
> Im thinking about doing complete reinstall on ad4+ad6 then.. Can I  
> do that? fdisk both with full partition on both, create a new  
> gmirror between ad6s1/ad4s1 (or should i go on ad4/ad6?), create  
> slices, use dump | restore (of course with apps shutdown so no data  
> is changed.. or at least nothing that I care about) to copy all  
> files from ad2 to new mirror.. what do I need to do more? bsdlabel - 
> B on both to write boot blocks? Is there anything else to think about?

Ok just for the record, I plugged both sata disks in, cleared them,  
created a new mirror on both of them, sliced up and dump -0 -L -f - /  
| restore -r -f - all filesystems, also bsdlabel -B. and what i  
missed in the above thext, fdisk -B  to write boot0 code.. Now its  
booted fine on the mirror!

altough, one thing that I got curious about. In the fdisk manpage it  
says -b can be used to change the bootcode.. and that default is / 
boot/mbr.. What is this? I checked md5 against boot0 and its not the  
same (altough I guess it might just be some boot0 with different  
config..). I never found any references to this mbr file in neither  
man pages or handbook.

Again, thanks for the help :)

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