9.1 RELENG_9 Unable to cleanly dismount root partition on shutdown

Kevin Oberman kob6558 at gmail.com
Mon Aug 27 19:06:51 UTC 2012

On Mon, Aug 27, 2012 at 11:42 AM, Warren Block <wblock at wonkity.com> wrote:
> 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.

Pretty good page, but I would really suggest that you also do either
4k or 1M alignment on your partitions. If you don't and use a disk
with 4K blocks (internally), you will have terrible performance. 1M is
recommended by Microsoft and used by Windows, but seems a bit
excessive to me.
R. Kevin Oberman, Network Engineer
E-mail: kob6558 at gmail.com

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