9.1 RELENG_9 Unable to cleanly dismount root partition on shutdown

[Warren Block]

On Mon, 27 Aug 2012, Matt Smith wrote:

> On 2012-08-27 14:56, Warren Block wrote:
>> 
>> Stefan called it.  The newfs is done on /dev/gpt/gptroot, no problem
>> there.  But when glabel writes to /dev/ada0p2--which is
>> /dev/gpt/gptroot, same thing, it overwrites the last block.  And then
>> the filesystem is mounted with the glabel device, which is actually
>> one block smaller than the filesystem expects.
>> 
>> Could be either the filesystem or GEOM that's causing the failure at 
>> shutdown.
>> 
>> Happily, those glabels aren't accomplishing anything useful and can
>> be skipped.  Removing the glabels and changing the devices in fstab
>> might be enough.  A more cautious approach would be to back up, newfs,
>> skip the glabel step, and then change the devices in fstab.
>
> As I said on a previous mail I did boot it with a USB stick and cleared the 
> glabel metadata and altered the fstab to point to both the GPT labels and the 
> raw UFS device and I still get the issue. So am I right in thinking then that 
> this has caused irreparable damage

To the filesystem?  Probably (weasel word) not.  The old instructions 
for gmirror used the last block out of a filesystem and there have been 
no notable reports of data loss.

One thing to mention is that SU+J might change what the filesystem does 
with that last block.  I'm avoiding SU+J until the dump problem is 
fixed, so have not experimented with that.

> and the only way I can fix this now is to newfs the filesystem again, 
> this time just using GPT labels and not using glabel at all?

I'll commit to it and say yes, that will work.

> This is the first time I've ever done a manually partitioned installation 
> with GPT and alignment, previously I've only ever used sysinstall with 
> non-aligned MBR installations, so it was a bit of a learning curve. If I do 
> have to newfs it again then I want to be sure that I'm doing the correct 
> things so that I don't find myself with any other issues. So does the rest of 
> what I did look fine?

No obvious problems jumped out at me.  Here are my notes:
http://www.wonkity.com/~wblock/docs/html/disksetup.html

The gpart version is halfway down.  I really need to switch that around.