topic Re: vgchange -- no volume groups found in Operating System - Linux

vgchange -- no volume groups found

Maaz — Thu, 28 Apr 2005 14:02:51 GMT

Hello Gurus,
I created the volume groups to create lvm, and then delete lvm(s) and volume groups. Now I received the "vgchange -- no volume groups found" message at system startup.
Remounting root filesystem in read-write mode: [ OK ]
Setting up Logical Volume Management: [ OK ]
vgchange -- no volume groups found

Activating swap partitions: [ OK ]
Finding module dependencies: [ OK ]
Setting up Logical Volume Management: [ OK ]
vgchange -- no volume groups found

What should I do .. so that this message doesnt come/appear

and Althoug i received the above mentioned message during system startup, but when I issue "dmesg |less", or "less /var/log/messages" i didnt find the "vgchange -- no volume groups found" .. why ?

Any Help will be highly appreciated.

Thanks n Regards
Maaz

Re: vgchange -- no volume groups found

Rick Garland — Thu, 28 Apr 2005 15:43:06 GMT

This is an order issue.

Trying to do the vgchange before the system startup reecognizes that LVM is installed.

Move the vgchange process after the LVM start process.

Re: vgchange -- no volume groups found

Steven E. Protter — Thu, 28 Apr 2005 17:09:18 GMT

strings /etc/lvmtab

get the name of the volume group and try this:

vgchange -a y /dev/vg01

or -n

It should work.

There may be a daemon running for lvm on Linux that must be running before any lvm commands run.

LVM is a features port, not a code port of HP-UX LVM. The later is a proprietary HP product and few ever see the source code.

SEP

Re: vgchange -- no volume groups found

Stuart Browne — Thu, 28 Apr 2005 20:40:30 GMT

That looks like a RedHat or Fedora boot up.

LVM is initlized about a 3rd of the way through of 'rc.sysinit'. There's a few lines which look like this:

# LVM initialization
if [ -f /etc/lvmtab ]; then
[ -e /proc/lvm ] || modprobe lvm-mod > /dev/null 2>&1
if [ -e /proc/lvm -a -x /sbin/vgchange ]; then
action $"Setting up Logical Volume Management:" /sbin/vgscan && /sbin/vgchange -a y
fi
fi

Simply put, if '/etc/lvmtab' exists, poke LVM stuff. Otherwise, don't. So, move '/etc/lvmtab' out of the way if you no longer have any LVM's.

Re: vgchange -- no volume groups found

Maaz — Thu, 28 Apr 2005 21:15:38 GMT

Millions of Thanks Dear Rick Garland, Steven E Protter, Stuart Browne, for the support/reply.
Yes Dear Stuart Browne u r right this is a RHL system.

one thing still remain ... why 'dmesg' didnt show me the "vgchange -- no volume groups found" I mean all startup messeges could be check via dmesg command.. but why not this message ?

I m highly grateful to u all.

Regards
Maaz

Re: vgchange -- no volume groups found

Stuart Browne — Thu, 28 Apr 2005 22:20:20 GMT

That's not quite accurate..

'dmesg' shows kernel logging messages, of which may or may not have a tty to show themselves on.

'vgchange' is a shell-level command which has stdout. This is why it doesn't show up in 'dmesg', because it executes in user-space, not at the kernel-level.

Re: vgchange -- no volume groups found

Maaz — Fri, 29 Apr 2005 14:12:57 GMT

Thanks again Dear Stuart Browne.

plz clear one more thing, the diff b/w the messeges in /var/log/boot.log and dmesg

Regards
Maaz

Re: vgchange -- no volume groups found

Stuart Browne — Fri, 29 Apr 2005 18:48:43 GMT

'/var/log/boot.log' on a RH/Fedora system is created by 'syslogd'.

From my '/etc/syslog.conf':

local7.* /var/log/boot.log

The messages are sent there from a command called 'initlog' (which has it's faculty set in '/etc/initlog.conf'), which gets called from '/etc/init.d/functions' by the startup routines.

On RH/Fedora machines, one of the the last things that gets done from '/etc/rc.d/rc.sysinit' is to dump the content of the 'dmesg' buffer to '/var/log/dmesg', so that the 'dmesg' output from the boot-cycle isn't lost over time.

Re: vgchange -- no volume groups found

Maaz — Fri, 29 Apr 2005 23:41:40 GMT

thank a million for reply.

i just wana know the "nature/type" or the diff b/w the "info" save in /var/log/dmesg, and /var/log/boot.log.
I mean which "type" of messages saved in /var/log/dmesg, and /var/log/boot.log

Thanks
Maaz

Re: vgchange -- no volume groups found

Stuart Browne — Sat, 30 Apr 2005 00:43:57 GMT

As I said before, it has to do with who's spitting the message out.

Daemons, and other user-space launched binaries have the ability to log either directly to the filesystem, or open TTY's, or to 'syslog'. They can write to their own log files, spit stuff to STDOUT or STDERR, or use the syslog systems to log to a 'facility.level' (i.e. mail.info). Also note that 'syslogd' is a process which runs a long time after the kernel first starts up.

The kernel isn't so lucky. The kernel will display things even before there's a filesystems available, possibly before there's any TTY's of any kind, and much before any processes are launched. So the kernel's output gets logged to the 'dmesg' buffer.