[linux-lvm] using LVM from two machines

[linux-lvm] using LVM from two machines

[Aman Shahi]

Hi,
I have LVM installed on two machines, both of which
are connected to the same storage(RAID BOX). Now I
need to do LVM operations from different machines at
different times. I will try to put a scenario and my
problem.

Lets say I have 2 disks( disk1, disk2). I have two
machines M1 and M2. Both machine see all the disks. If
I create a VG called VG1 on disk1 from M1, and do a
vgscan on M2, the VG VG1 can be seen from both the
machines. I then create VG called VG2 from M2 on
disk2.

So basically I created 2 VG's from two different
machines, but both is visible on both machines. 

Now if I delete a VG from a machine from one machine,
any LVM operations from the other machine fails with
the message "VGDA in kernel and LVMTAB are not
consistent". I manually removed /dev/VG1 and /etc/lvm*
from the other machine and did a vgscan , but still I
get the message "VGDA in kernel and lvmtab are
inconsistent, please run vgscan". Running vgscan does
not help.

How can I modify this VGDA in kernel in the other
machine so that any LVM operation on one machine can
be reflected in the other machine. Or can I do
something like  "deactivating" the data that is kept
in the kernel, so that the LVM just relies on the
information in the disks, or something like that. I
mean I need to be able to use LVM from two different
machine as if they were one.

regards,
Aman Shahi.

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Re: [linux-lvm] using LVM from two machines

[Patrick Caulfield]

On Wed, Aug 01, 2001 at 08:24:51AM -0700, Aman Shahi wrote:
> Hi,
> I have LVM installed on two machines, both of which
> are connected to the same storage(RAID BOX). Now I
> need to do LVM operations from different machines at
> different times. I will try to put a scenario and my
> problem.
> 
> Lets say I have 2 disks( disk1, disk2). I have two
> machines M1 and M2. Both machine see all the disks. If
> I create a VG called VG1 on disk1 from M1, and do a
> vgscan on M2, the VG VG1 can be seen from both the
> machines. I then create VG called VG2 from M2 on
> disk2.
> 
> So basically I created 2 VG's from two different
> machines, but both is visible on both machines. 
> 
> Now if I delete a VG from a machine from one machine,
> any LVM operations from the other machine fails with
> the message "VGDA in kernel and LVMTAB are not
> consistent". I manually removed /dev/VG1 and /etc/lvm*
> from the other machine and did a vgscan , but still I
> get the message "VGDA in kernel and lvmtab are
> inconsistent, please run vgscan". Running vgscan does
> not help.
> 
> How can I modify this VGDA in kernel in the other
> machine so that any LVM operation on one machine can
> be reflected in the other machine. Or can I do
> something like  "deactivating" the data that is kept
> in the kernel, so that the LVM just relies on the
> information in the disks, or something like that. I
> mean I need to be able to use LVM from two different
> machine as if they were one.

The short answer is "don't do that!". We are currently working
of a cluster-enabled version of LVM (I don't have any release dates I'm afraid)
that will enable you to do what you want and more.

The only way to achieve what you want to do at the moment is to unload the VGs
on one machine (vgchange -ay after closing all the volumes), make the changes
on the other machine and then re-run vgscan on the first machine and remount the
volumes. This applies to *any* changes you make to the LVM configuration.

Be careful !

patrick

Re: [linux-lvm] using LVM from two machines

[AJ Lewis]

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On Wed, Aug 01, 2001 at 05:08:28PM +0100, Patrick Caulfield wrote:
> The only way to achieve what you want to do at the moment is to unload the VGs
> on one machine (vgchange -ay after closing all the volumes), make the changes
                  ^^^^^^^^^^^^
i believe patrick meant 'vgchange -an' here.

> on the other machine and then re-run vgscan on the first machine and remount the
> volumes. This applies to *any* changes you make to the LVM configuration.

-- 
AJ Lewis
Sistina Software Inc.                  Voice:  612-638-0500
1313 5th St SE, Suite 111              Fax:    612-638-0500
Minneapolis, MN 55414                  E-Mail: lewis@sistina.com
http://www.sistina.com

Current GPG fingerprint = 3B5F 6011 5216 76A5 2F6B  52A0 941E 1261 0029 2648
Get my key at: http://www.sistina.com/~lewis/gpgkey
 (Unfortunately, the PKS-type keyservers do not work with multiple sub-keys)

-----Begin Obligatory Humorous Quote----------------------------------------
The three most dangerous things are a programmer with a soldering iron, a
manager who codes, and a user who gets ideas.
-----End Obligatory Humorous Quote------------------------------------------

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Re: [linux-lvm] using LVM from two machines

[Patrick Caulfield]

On Wed, Aug 01, 2001 at 12:38:00PM -0500, AJ Lewis wrote:
> On Wed, Aug 01, 2001 at 05:08:28PM +0100, Patrick Caulfield wrote:
> > The only way to achieve what you want to do at the moment is to unload the VGs
> > on one machine (vgchange -ay after closing all the volumes), make the changes
>                   ^^^^^^^^^^^^
> i believe patrick meant 'vgchange -an' here.


He did! Thanks AJ. 


patrick

Re: [linux-lvm] using LVM from two machines

[Harald Milz]

In article <20010801170828.G2603@tykepenguin.com>, Patrick Caulfield <caulfield@sistina.com> wrote:
> The only way to achieve what you want to do at the moment is to unload the VGs
> on one machine (vgchange -ay after closing all the volumes), make the changes
> on the other machine and then re-run vgscan on the first machine and remount the
> volumes. This applies to *any* changes you make to the LVM configuration.

In a cluster context (a.k.a. failover scenario) this is the only reasonable
way to do it. 

-- 
Harald Milz           |     hm@linux-magazin.de     | Xerox never comes up
Linux New Media AG    | phone  +49 (0) 89 993411-20 | with anything original.
Stefan-George-Ring 24 | fax    +49 (0) 89 993411-99 | 
D-81929 Muenchen      | http://www.linux-magazin.de | 

Re: [linux-lvm] using LVM from two machines

[Tracy R Reed]

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On Wed, Aug 01, 2001 at 08:24:51AM -0700, Aman Shahi wrote:
> I have LVM installed on two machines, both of which
> are connected to the same storage(RAID BOX). Now I
> need to do LVM operations from different machines at
> different times. I will try to put a scenario and my
> problem.

Sounds like you want GFS. www.gobalfilesystem.org

-- 
Tracy Reed      http://www.ultraviolet.org
This is Linux Country. On a quiet night, you can hear Windows NT reboot!
-

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