Lustre discuss - Jul 2010 - tunefs.lustre --print fails on mounted mdt/ost with mmp

Just checking to be sure this isn''t a known bug or problem.  I
couldn''t
find a bz for this, but it would appear that tunefs.lustre --print fails
on a lustre mdt or ost device if mounted with mmp.

Is this expected behavior?

TIA

mds1-gps:~ # tunefs.lustre --print /dev/mapper/mdt1
checking for existing Lustre data: not found

tunefs.lustre FATAL: Device /dev/mapper/mdt1 has not been formatted with
mkfs.lustre
tunefs.lustre: exiting with 19 (No such device)
mds1-gps:~ # 


Command works fine when unmounted.

-- 
Sent from my wired giant hulking workstation

Nate Pearlstein - npearl at sgi.com - Product Support Engineer

On 2010-07-14, at 13:29, Nate Pearlstein wrote:
> Just checking to be sure this isn''t a known bug or problem.  I
couldn''t
> find a bz for this, but it would appear that tunefs.lustre --print fails
> on a lustre mdt or ost device if mounted with mmp.
> 
> Is this expected behavior?
Not really expected...  It is reading the "mountdata" file via
debugfs, so that should be safe even on a mounted filesystem, but it
doesn''t work with MMP:

# debugfs -c -R stats /dev/vgbackup/lvtest 
debugfs 1.41.10.sun2 (24-Feb-2010)
/dev/vgbackup/lvtest: MMP: device currently active while opening filesystem
stats: Filesystem not open

This is already fixed in our next release of e2fsprogs, however, thanks to a
patch Jim Garlick @ LLNL.  It is the first hunk of the patch at:

https://bugzilla.lustre.org/attachment.cgi?id=30441
> mds1-gps:~ # tunefs.lustre --print /dev/mapper/mdt1
> checking for existing Lustre data: not found
> 
> tunefs.lustre FATAL: Device /dev/mapper/mdt1 has not been formatted with
> mkfs.lustre
This error message should probably be fixed also.


Cheers, Andreas
--
Andreas Dilger
Lustre Technical Lead
Oracle Corporation Canada Inc.

On Wednesday, July 14, 2010, Andreas Dilger wrote:
> On 2010-07-14, at 13:29, Nate Pearlstein wrote:
> > Just checking to be sure this isn''t a known bug or problem. 
I couldn''t
> > find a bz for this, but it would appear that tunefs.lustre --print
fails
> > on a lustre mdt or ost device if mounted with mmp.
> > 
> > Is this expected behavior?
> 
> Not really expected...  It is reading the "mountdata" file via
debugfs, so
> that should be safe even on a mounted filesystem, but it doesn''t
work with
> MMP:
> 
> # debugfs -c -R stats /dev/vgbackup/lvtest
> debugfs 1.41.10.sun2 (24-Feb-2010)
> /dev/vgbackup/lvtest: MMP: device currently active while opening filesystem
> stats: Filesystem not open
> 
> This is already fixed in our next release of e2fsprogs, however, thanks to
> a patch Jim Garlick @ LLNL.  It is the first hunk of the patch at:
> 
> https://bugzilla.lustre.org/attachment.cgi?id=30441
Actually not required, as it opens the device read-only. I would recommend the 
first patch from 

https://bugzilla.lustre.org/show_bug.cgi?id=22421 

that also allows to run other e2fs tools, such as "e2fsck -n",
"dumpe2fs -h"
and "tunefs.lustre --print" on mounted devices.

Cheers,
Bernd