[linux-lvm] Chicken and egg problem..

[linux-lvm] Chicken and egg problem..

[Georges Giralt]

Hello !
As I've previously said, I plan to make my RedHat 7.1 (kernel 2.4.5) a pure LVM 
machine.
To do so, I've build the 1.0.4 version of LVM into the kernel (with the NCR SCSI 
driver). As to avoid an initrd. Simple is beautifull...

In the sysinit rc script, Redhat has put a vg activation command, but....
My kernel panics, as it is unable to mount root, as the LVM activation commands 
are after the root fsck (and mount..)

If I put the LVM activation lines early, in the sysinit script, these commands 
complains beeing not able to access /etc/lvmtab....

So I'm face with a chicken and egg problem. Which one was first ?
Any idea ? It will be fun for me to have this configuration set up and running !
Regards

Re: [linux-lvm] Chicken and egg problem..

[Steven Lembark]

-- Georges Giralt <georges.giralt@free.fr>

> Hello !
> As I've previously said, I plan to make my RedHat 7.1 (kernel 2.4.5) a
> pure LVM  machine.
> To do so, I've build the 1.0.4 version of LVM into the kernel (with the
> NCR SCSI  driver). As to avoid an initrd. Simple is beautifull...
>
> In the sysinit rc script, Redhat has put a vg activation command, but....
> My kernel panics, as it is unable to mount root, as the LVM activation
> commands  are after the root fsck (and mount..)
>
> If I put the LVM activation lines early, in the sysinit script, these
> commands  complains beeing not able to access /etc/lvmtab....

The kernel panic is extactly why you probably wouldn't
want to use only LVM on the system. Leaving the root
volume (a.k.a., '/'), primary swap and probably /var on
the first three partitions of the boot device will make
your life enormously simpler in the long run.

This is pretty much the only way you'll be able to
convienently recover from any LVM problems in the future.
Otherwise you'll need bootable media floating around.

--
Steven Lembark                               2930 W. Palmer
Workhorse Computing                       Chicago, IL 60647
                                            +1 800 762 1582

Re: [linux-lvm] Chicken and egg problem..

[Georges Giralt]

En r�ponse � Steven Lembark <lembark@wrkhors.com>:

> 
> 
> -- Georges Giralt <georges.giralt@free.fr>
> 
> > Hello !
> > As I've previously said, I plan to make my RedHat 7.1 (kernel 2.4.5)
> a
> > pure LVM  machine.
> > To do so, I've build the 1.0.4 version of LVM into the kernel (with
> the
> > NCR SCSI  driver). As to avoid an initrd. Simple is beautifull...
> >
> > In the sysinit rc script, Redhat has put a vg activation command,
> but....
> > My kernel panics, as it is unable to mount root, as the LVM
> activation
> > commands  are after the root fsck (and mount..)
> >
> > If I put the LVM activation lines early, in the sysinit script,
> these
> > commands  complains beeing not able to access /etc/lvmtab....
> 
> The kernel panic is extactly why you probably wouldn't
> want to use only LVM on the system. Leaving the root
> volume (a.k.a., '/'), primary swap and probably /var on
> the first three partitions of the boot device will make
> your life enormously simpler in the long run.
Yes and no....
I use HP boxes, on which LVM is native.
My computer has been upgraded from RH4.1 to 7.1 with all the steps in beetween.
This is why I would use LVM on my boot disk.
Tired re creating a new / or /var and moving data from one file system to the 
next.
And I always have bootable floppy/CD floating around...
My question was in fact to learn how to make the LVM information static on the 
/etc directory. (if this information is not valid, the system will not boot 
anyway, so it doesn't hurt) Of course, I must rebuild these files if I change 
the volume group holding the / filesystem.... Something which is easyly done on 
an HP machine...
> 
> This is pretty much the only way you'll be able to
> convienently recover from any LVM problems in the future.
> Otherwise you'll need bootable media floating around.
> 
> --
> Steven Lembark                               2930 W. Palmer
> Workhorse Computing                       Chicago, IL 60647
>                                             +1 800 762 1582
> 
> _______________________________________________
> linux-lvm mailing list
> linux-lvm@sistina.com
> http://lists.sistina.com/mailman/listinfo/linux-lvm
> read the LVM HOW-TO at http://www.sistina.com/lvm/Pages/howto.html
> 

Re: [linux-lvm] Chicken and egg problem..

[Brian J. Murrell]

On Wed, Nov 21, 2001 at 02:30:25AM -0600, Steven Lembark wrote:
> 
> The kernel panic is extactly why you probably wouldn't
> want to use only LVM on the system.

I do it.  Only my boot partition is a regular ol' partition.  I won't
say I haven't had problems that I had to recover from in the past with
an LVM root, but luckily enough my distro vendor's LVM support is
decent and their BOOT kernel/media has an LVM module built for it.

> Leaving the root
> volume (a.k.a., '/'), primary swap and probably /var on
> the first three partitions of the boot device will make
> your life enormously simpler in the long run.

I completely disagree.  Eventually you will get to a point where an
upgrade of your system will require more space in / or /usr and even
just normal usage will want more space in /var.  Being able to expand
these easily with LVM is awesome!

> This is pretty much the only way you'll be able to
> convienently recover from any LVM problems in the future.

Just use a good boot disk.  You are even luckier if your distro
vendor's stock kernel and/or media support LVM.

> Otherwise you'll need bootable media floating around.

Of course.  Don't you always?  :-)

b.

-- 
Brian J. Murrell

Re: [linux-lvm] Chicken and egg problem..

[Brian J. Murrell]

On Wed, Nov 21, 2001 at 01:53:17PM +0100, Georges Giralt wrote:
> 
> As I've previously said, I plan to make my RedHat 7.1 (kernel 2.4.5) a pure LVM 
> machine.
> To do so, I've build the 1.0.4 version of LVM into the kernel (with the NCR SCSI 
> driver). As to avoid an initrd. Simple is beautifull...

Simple might be beautiful but compiling LVM into the kernel does not
alleviate the need for an initrd if your root fs is on an LVM device.

> In the sysinit rc script, Redhat has put a vg activation command, but....
> My kernel panics, as it is unable to mount root, as the LVM activation commands 
> are after the root fsck (and mount..)
> 
> If I put the LVM activation lines early, in the sysinit script, these commands 
> complains beeing not able to access /etc/lvmtab....

Now you know why you need an initrd.  :-)

b.

-- 
Brian J. Murrell

Re: [linux-lvm] Chicken and egg problem..

[Steven Lembark]

-- "Brian J. Murrell" <724b581f59b221086926026402b50126@interlinx.bc.ca>

> On Wed, Nov 21, 2001 at 02:30:25AM -0600, Steven Lembark wrote:
>>
>> The kernel panic is extactly why you probably wouldn't
>> want to use only LVM on the system.
>
> I do it.  Only my boot partition is a regular ol' partition.  I won't
> say I haven't had problems that I had to recover from in the past with
> an LVM root, but luckily enough my distro vendor's LVM support is
> decent and their BOOT kernel/media has an LVM module built for it.

Luck has a rather nasty way of running out just when
you need the system. I've spent way too much time
helping extricate people from LVM problems to run
my root file system on it. The "all LVM" systems
from HP and Sun depend on a non-braindead boot ROM
and the ability to fake out the file system with
sequentail LV's that look to the boot loader like
partitions. On HP's this lets you boot -lm, fix
things and reboot. Lacking this option on Intel
systems, I'd make a point of leaving the main boot
area on a native hardware format.

>
>> Leaving the root
>> volume (a.k.a., '/'), primary swap and probably /var on
>> the first three partitions of the boot device will make
>> your life enormously simpler in the long run.
>
> I completely disagree.  Eventually you will get to a point where an
> upgrade of your system will require more space in / or /usr and even
> just normal usage will want more space in /var.  Being able to expand
> these easily with LVM is awesome!

Who said anything about not having /usr on LVM? If the root
(basically /etc, /lib and a wholelotta mount points) is a
partition and your primary swap is also then you can boot just
as easily without LVM as with it. I've been running with / on
a 128MB partition for years and never pushed it past 50%. Same
for /var: adding a few choice mount points can reduce the need
for expanding the main storage enormously. If /var/log, for
example, is on a partition it makes life easier trying to
diagnose any problems.


> Just use a good boot disk.  You are even luckier if your distro
> vendor's stock kernel and/or media support LVM.

Even luckier than that if they're patched to exactly the
same level you are and can read your LVM system. This only
has to blow up once before you get to spend a weekend [or
worse] fixing the problem.



--
Steven Lembark                               2930 W. Palmer
Workhorse Computing                       Chicago, IL 60647
                                            +1 800 762 1582