setup journaling for root partition

[Warren Block]

On Thu, 23 May 2013, Torsten Hantzsche wrote:

> On Thu, 23 May 2013, s m wrote:
>
>
>> thanks,
>> 
>> i do as you said, but after loading gjournal, dd says "operation not
>> permitted".
>> gjournal clear says "operation not permitted" too and therefore "gjournal
>> label" is not done and say previous error (gjournal cannot clear metadata
>> on ad3s1a: operation not permitted). and -v return no extra log.
>> 
>> i don't know why i can not do any thing in fixit mode:(
>> 
>> is this a true procedure? i mean maybe i should do any thing else  because
>> freebsd handbook set journaling for user partition in single user mode not
>> in fixit mode. i test it and it works well, but for root partition i can
>> not do the same because root partition can not be unmount in single user
>> mode.
>> 
>> any hints or comments are really appreciated.
>> thanks in advance
>> 
>
> Hi,
>
> i remember having similar error messages with glabel some years ago.
> The solution was found in "man 4 geom" in section DIAGNOSTICS:
>
> I had to set "kern.geom.debugflags=0x10" to enable the "foot shooting" mode.
>
> Maybe this could help you too?

For certain values of "help". :)

If geom won't let you write to part of a disk, it's because it thinks 
that part of the disk is already in use, usually by a mounted 
filesystem.  Overwriting part of a filesystem is not guaranteed to lose 
data.  But why take the chance?

Better to boot from mfsBSD (http://mfsbsd.vx.sk/).  Possibly better yet 
to use SUJ, which can be enabled with tunefs with the root partition 
mounted read-only in single user mode.  SUJ has its own problems, 
though.