[SOLVED] Re: labelling root file system (RELENG_8)

[Jeremy Chadwick]

On Wed, Jun 08, 2011 at 09:55:15AM -0700, Jeremy Chadwick wrote:
> On Wed, Jun 08, 2011 at 07:40:03PM +0300, Andriy Gapon wrote:
> > on 08/06/2011 19:26 Jeremy Chadwick said the following:
> > > I have the exact same question except not with regards to labels but
> > > toggling TRIM capability on the root filesystem.
> > > 
> > > - Start system
> > > - At loader, boot single-user (option 4)
> > > - At prompt choose /bin/sh
> > > - mount -a
> > 
> > I think that this is a culprit.
> 
> I'll try removing this step.
> 
> > > - tunefs -t enable /dev/ada0s1a --- fails
> > 
> > Shouldn't you have / mounted r/o here?
> > BTW, AFAIR, *re*-mounting root read-only won't help; it needs to have never been
> > mounted r/w.
> 
> I'm a little confused by this sentence, so my apologise in advance.  /
> is mounted read-only in single-user by default.  Did you mean I should
> make it r/w by doing "mount -u -o rw /" ?  I may have omitted this step.
> 
> I will re-verify the exact procedure and exact steps in a moment, and
> reply here.
> 
> > > - sysctl kern.geom.debugflags=16
> > > - tunefs -t enable /dev/ada0s1a --- works
> > > - tunefs -p /dev/ada0s1a -- shows TRIM enabled
> > > - reboot
> > 
> > I think that at this step your superblock on disk gets re-written with its copy in
> > memory which has never been updated.  But not sure.
> 
> Hmm, I sure hope that isn't the case.  That would mean the only time a
> person can use tunefs on a root filesystem is when they either do it
> manually during the FreeBSD installation (adding "-t" to the list of
> newfs flags in the filesystem creation UI), or if they boot off of some
> other medium (USB flash drive, CD, PXE, etc.).

Interestingly enough, the long procedure I originally described is
probably what was causing the problem.  Not sure how to phrase it.

The exact procedure which worked was:

- Start system
- Boot into single-user
- Hit enter at prompt (choose /bin/sh)
- mount --- shows root filesystem mounted read-only (normal)
- tunefs -t enable /dev/ada0s1a --- says it enabled TRIM support
- tunefs -p /dev/ada0s1a --- shows TRIM support enabled
- reboot
- After system starts, as root: tunefs -p /dev/ada0s1a --- shows TRIM
  enabled

So the extra rigmarole I was doing somehow caused the problem.

-- 
| Jeremy Chadwick                                   jdc at parodius.com |
| Parodius Networking                       http://www.parodius.com/ |
| UNIX Systems Administrator                   Mountain View, CA, US |
| Making life hard for others since 1977.               PGP 4BD6C0CB |