topic Re: / file system mounted in /dev/root file automatically how? in Operating System - HP-UX

/ file system mounted in /dev/root file automatically how?

HPquestion — Fri, 18 Jan 2008 20:34:29 GMT

Its HP UX 11.23. Today noticed that ROOT file system got mounted in /dev/root instead of
/dev/vg00/lvol3.

Some how / entry in /etc/fstab got changed ( in april 2007) .And in between we had 2 reboots and we didn't have any error at all during the reboot. Looks like OS is smart enough to use /dev/root automatically? Could anybody please explain me the possibilities.
Are we in trouble?

Re: / file system mounted in /dev/root file automatically how?

Robert-Jan Goossens — Fri, 18 Jan 2008 20:50:53 GMT

Hi,

Could you post the output of

# lvdisplay -v /dev/vg01/lvol3

Regards,
Robert-Jan

Re: / file system mounted in /dev/root file automatically how?

Laurent Menase — Fri, 18 Jan 2008 20:51:00 GMT

It uses the information positionned by lvlnboot
for /dev/root.

Re: / file system mounted in /dev/root file automatically how?

Robert-Jan Goossens — Fri, 18 Jan 2008 20:52:32 GMT

make that vg00 :-)

# lvdisplay -v /dev/vg00/lvol3

Re: / file system mounted in /dev/root file automatically how?

HPquestion — Fri, 18 Jan 2008 21:04:04 GMT

lvdisplay -v /dev/vg00/lvol3
--- Logical volumes ---
LV Name /dev/vg00/lvol3
VG Name /dev/vg00
LV Permission read/write
LV Status available/syncd
Mirror copies 1
Consistency Recovery MWC
Schedule parallel
LV Size (Mbytes) 576
Current LE 36
Allocated PE 72
Stripes 0
Stripe Size (Kbytes) 0
Bad block off
Allocation strict/contiguous
IO Timeout (Seconds) default

--- Distribution of logical volume ---
PV Name LE on PV PE on PV
/dev/dsk/c2t1d0s2 36 36
/dev/dsk/c2t0d0s2 36 36

--- Logical extents ---
LE PV1 PE1 Status 1 PV2 PE2 Status 2
00000 /dev/dsk/c2t1d0s2 00275 current /dev/dsk/c2t0d0s2 00275 current
00001 /dev/dsk/c2t1d0s2 00276 current /dev/dsk/c2t0d0s2 00276 current
00002 /dev/dsk/c2t1d0s2 00277 current /dev/dsk/c2t0d0s2 00277 current
00003 /dev/dsk/c2t1d0s2 00278 current /dev/dsk/c2t0d0s2 00278 current
00004 /dev/dsk/c2t1d0s2 00279 current /dev/dsk/c2t0d0s2 00279 current
00005 /dev/dsk/c2t1d0s2 00280 current /dev/dsk/c2t0d0s2 00280 current
00006 /dev/dsk/c2t1d0s2 00281 current /dev/dsk/c2t0d0s2 00281 current
00007 /dev/dsk/c2t1d0s2 00282 current /dev/dsk/c2t0d0s2 00282 current
00008 /dev/dsk/c2t1d0s2 00283 current /dev/dsk/c2t0d0s2 00283 current
00009 /dev/dsk/c2t1d0s2 00284 current /dev/dsk/c2t0d0s2 00284 current
00010 /dev/dsk/c2t1d0s2 00285 current /dev/dsk/c2t0d0s2 00285 current
00011 /dev/dsk/c2t1d0s2 00286 current /dev/dsk/c2t0d0s2 00286 current
00012 /dev/dsk/c2t1d0s2 00287 current /dev/dsk/c2t0d0s2 00287 current
00013 /dev/dsk/c2t1d0s2 00288 current /dev/dsk/c2t0d0s2 00288 current
00014 /dev/dsk/c2t1d0s2 00289 current /dev/dsk/c2t0d0s2 00289 current
00015 /dev/dsk/c2t1d0s2 00290 current /dev/dsk/c2t0d0s2 00290 current
00016 /dev/dsk/c2t1d0s2 00291 current /dev/dsk/c2t0d0s2 00291 current
00017 /dev/dsk/c2t1d0s2 00292 current /dev/dsk/c2t0d0s2 00292 current
00018 /dev/dsk/c2t1d0s2 00293 current /dev/dsk/c2t0d0s2 00293 current
00019 /dev/dsk/c2t1d0s2 00294 current /dev/dsk/c2t0d0s2 00294 current
00020 /dev/dsk/c2t1d0s2 00295 current /dev/dsk/c2t0d0s2 00295 current
00021 /dev/dsk/c2t1d0s2 00296 current /dev/dsk/c2t0d0s2 00296 current
00022 /dev/dsk/c2t1d0s2 00297 current /dev/dsk/c2t0d0s2 00297 current
00023 /dev/dsk/c2t1d0s2 00298 current /dev/dsk/c2t0d0s2 00298 current
00024 /dev/dsk/c2t1d0s2 00299 current /dev/dsk/c2t0d0s2 00299 current
00025 /dev/dsk/c2t1d0s2 00300 current /dev/dsk/c2t0d0s2 00300 current
00026 /dev/dsk/c2t1d0s2 00301 current /dev/dsk/c2t0d0s2 00301 current
00027 /dev/dsk/c2t1d0s2 00302 current /dev/dsk/c2t0d0s2 00302 current
00028 /dev/dsk/c2t1d0s2 00303 current /dev/dsk/c2t0d0s2 00303 current
00029 /dev/dsk/c2t1d0s2 00304 current /dev/dsk/c2t0d0s2 00304 current
00030 /dev/dsk/c2t1d0s2 00305 current /dev/dsk/c2t0d0s2 00305 current
00031 /dev/dsk/c2t1d0s2 00306 current /dev/dsk/c2t0d0s2 00306 current
00032 /dev/dsk/c2t1d0s2 00307 current /dev/dsk/c2t0d0s2 00307 current
00033 /dev/dsk/c2t1d0s2 00308 current /dev/dsk/c2t0d0s2 00308 current
00034 /dev/dsk/c2t1d0s2 00309 current /dev/dsk/c2t0d0s2 00309 current
00035 /dev/dsk/c2t1d0s2 00310 current /dev/dsk/c2t0d0s2 00310 current

Re: / file system mounted in /dev/root file automatically how?

Robert-Jan Goossens — Fri, 18 Jan 2008 21:06:24 GMT

Looks okay.

# mv /etc/mnttab /etc/mnttab.old
# mount -a
to recreate the mnttab file

# bdf

Robert-Jan

Re: / file system mounted in /dev/root file automatically how?

HPquestion — Fri, 18 Jan 2008 21:11:13 GMT

Thanks for all your help! We have entry in /etc/fstab.
/lvol3 / vxfs delaylog 0 1

And we have the befow line in /etc/mntab
/dev/root / vxfs ioerror=nodisable,log,dev=40000003 0 0 1195429301

Should I change fstab to /dev/root to match with /etc/mnttab file?

This is production box and the last 2 reboot worked correctly.

Re: / file system mounted in /dev/root file automatically how?

Mridul Shrivastava — Fri, 18 Jan 2008 21:13:06 GMT

The above answer tell you how to fix the problem.
But the usual reason for having /dev/root mounted on / is that someone completed a boot (init 3?) while the system was in LVM maintenance mode.
One should always do a reboot or shutdown -ry 0 from LVM maintenance mode.

Re: / file system mounted in /dev/root file automatically how?

Robert-Jan Goossens — Fri, 18 Jan 2008 21:15:09 GMT

You do not have to change the /etc/fstab file, you just have to recreate the /etc/mnttab file. There is no harm in doing that online on a production box.

# mv /etc/mnttab /etc/mnttab.old
# mount -a
will recreate the mnttab
# bdf
to check.

Re: / file system mounted in /dev/root file automatically how?

Mridul Shrivastava — Fri, 18 Jan 2008 21:15:46 GMT

It shouldn't be /dev/root so don't change fstab...

Please rename the mnttab file and then recreate it using mount -a
Then execute bdf it should show /dev/vg00/lvol3 mounted on root. This is the correct.

Re: / file system mounted in /dev/root file automatically how?

HPquestion — Fri, 18 Jan 2008 21:22:18 GMT

Thanks! Last two reboot (clean reboot) worked correctly with /dev/root. Problem is that our fstab has a typo.
Instead of
/dev/vg00/lv0l3 / vxfs delaylog 0 1

we have the below entry there.
/lvol3 / vxfs delaylog 0 1

We did clean reboot earlier. We didn't use init 3.

Re: / file system mounted in /dev/root file automatically how?

Mridul Shrivastava — Fri, 18 Jan 2008 21:33:02 GMT

Then I would recommend to populate the fstab with the correct information, change it to /dev/vg00/lvol3 and then follow the steps mentioned above.

It is purely safe and will not cause any harm to the system.

/dev/root means in past it has been booted in run level 3 from LVM maintenance mode. This is not a normal scenario.

Re: / file system mounted in /dev/root file automatically how?

Robert-Jan Goossens — Fri, 18 Jan 2008 21:33:15 GMT

Then you will have to edit the /etc/fstab, change lvol3 into /dev/vg00/lvol3 and then move and recreate the mnttab file.

Re: / file system mounted in /dev/root file automatically how?

HPquestion — Fri, 18 Jan 2008 21:46:43 GMT

Thanks again! As its a production system do you see any possibily of root file system corruption if I exeute the suggested changes? I am still trying to understand the pieces before I do anything in production :-) .Is that mean my / files which are located in /dev/root will be moved to /dev/vg00/lvo3 if I do the change?

Current BDF output is :
/dev/root 589824 324944 262816 55% /

root>cd /
root>ls
.gpmhp-ricr3prd home sapmnt
.hh backup lib sbin
.lsof_ricr3prd bin lost+found stand
.mozilla dbcopy net tmp
.mozilla-license dead.letter newprofile transports
.profile depot opt usr
.q4rc.pl dev oracle var
.sh_history devnull patches.txt
.ssh dvd sapbasis
.sw etc sapinst

Re: / file system mounted in /dev/root file automatically how?

Robert-Jan Goossens — Fri, 18 Jan 2008 21:52:22 GMT

--
Thanks again! As its a production system do you see any possibily of root file system corruption if I exeute the suggested changes? I am still trying to understand the pieces before I do anything in production :-) .
--

There is no possibily of root filesystem corruption.

--
Is that mean my / files which are located in /dev/root will be moved to /dev/vg00/lvo3 if I do the change?
--

Well yes and no, curtain HP commands will not work properly like ignite's make_tape/net_recovery commands.

Regards,
Robert-Jan

Re: / file system mounted in /dev/root file automatically how?

HPquestion — Fri, 18 Jan 2008 21:57:06 GMT

"Well yes and no, curtain HP commands will not work properly like ignite's make_tape/net_recovery commands."

Now I am really scared. Is that means that I may loose some files and directories as it will move the existing stuff from /dev/root to /dev/vg00/lv03?

Re: / file system mounted in /dev/root file automatically how?

Robert-Jan Goossens — Fri, 18 Jan 2008 22:02:08 GMT

No :-) you will not loose files, your / root filesystem itself will not change, you just have to change the mount information/administration regarding the root filesystem.

Re: / file system mounted in /dev/root file automatically how?

HPquestion — Fri, 18 Jan 2008 22:24:05 GMT

Thanks again! Our /etc/fstab file got corrupted. I found 2 lines there where our previous admin made the typos. After that we had around 2 reboot (using sam shutdown -r option), do you think that
fstab typo/corruption can lead OS to
mount root in /dev/root?

Re: / file system mounted in /dev/root file automatically how?

Mridul Shrivastava — Sat, 19 Jan 2008 13:20:58 GMT

yes there is a possibility of that. I still think that someone had booted it to level 3 from LVM then might have noticed /dev/root instead of /dev/vg00/lvol3.
After that he was trying to change the fstab accordingly and it got corrupted ,hence it is still mounted on /dev/root even after 2 successful reboots.

Re: / file system mounted in /dev/root file automatically how?

HPquestion — Sat, 19 Jan 2008 17:07:05 GMT

Thanks again!

Questions on fixing the error:
1.As its a SAP production box , do we need to shutdown sap and database before doing "mount -a" .
2.Looks like we had /dev/root situation happened 2 months before. In between I had to increase one file system which is mounted at /usr/sap. Do you see any error if I have to do "mount -a" after fixing the errors in fstab file?

3. Trying to understand more about /etc/mnttab file. When /etc/mnttab file get updated and used ?
Is it during the reboot and "mount -a"? Is fstab feeds mnttab all the time?
If fstab file get corrupted due to typo or so,how /etc/mnttab get updated during reboot?

Questions on " Why it happened"

I did all the reboots and always used shutdown -r.Didn't use init 3 at all.

Do we have any system log other than /var/adm/syslog to check the previous reboot procedures happened in the system?

Last time we had a power crash on Nov 18th and I had to do "shutdown -h" to shutdown the box.

Is he below syslog looks normal?

Nov 18 11:50:14 guard_tap[28917]: connect: Network is unreachable
Nov 18 11:50:32 su: + console -root
Nov 18 11:54:29 HP-PRM: [9446]: prmconfig: configuration reset
Nov 18 11:55:11 /usr/sbin/envd[2665]: terminated by signal 15
Nov 18 11:55:12 diagmond[2655]: Exit due to user requested abort
Nov 18 11:55:13 FontServer[2433]: terminating
Nov 18 11:55:13 sshd[1539]: Received signal 15; terminating.
Nov 18 11:55:28 cimserver[9716]: Shutdown timeout expired. Forced shutdown initiated.
Nov 18 11:55:41 inetd[1748]: Going down on signal 15
Nov 18 11:59:27 rpcbind: terminate: rpcbind terminating on signal. Restart with "rpcbind -w"
Nov 18 11:59:28 su: + tty?? root-sfmdb
Nov 18 11:59:32 syslogd: going down on signal 15