[linux-lvm] Quorums / VGDAs
Heinz J . Mauelshagen
mauelshagen at sistina.com
Wed Sep 11 05:57:56 UTC 2002
On Tue, Sep 10, 2002 at 11:56:16AM -0700, Anthony Johnson wrote:
> I'm trying to find information on the availability factors of LVM. As I
> understand it, a quorum is required for a volume group to be available.
> I have some questions in this regard:
> 1) What defines a quorum - over 50% of the PVs in the VG, or over 50%
> of the VGDAs?
VG quorum is given in case all of its PVs are available.
> 2) How many VGDAs are stored on each physical volume. From AIX
> experience, this varied depending on the number of PVs in the VG.
In the LVM1 metadata there's allways 1 VGDA on each PV which has internal
With the new LVM2 formats you can have as many VGDA copies as you like.
> 3) If quorum is lost on an active VG, is the entire VG automatically
> varied off?
No, it will stay accessable with the exception of the dead PV(s).
> 4) Can a VG without quorum be forcefully varied on?
With LVM1.1 (see CVS; WARNING: his is interim development code!) and with final
LVM2 later this year, you can activate a VG which has lost quorum.
> 5) Can quorum checking be disabled?
No, but with the above SW you can activate the VG in case there's
at least 1 PV still accessable.
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> linux-lvm at sistina.com
> read the LVM HOW-TO at http://www.sistina.com/lvm/Pages/howto.html
Heinz -- The LVM Guy --
*** Software bugs are stupid.
Nevertheless it needs not so stupid people to solve them ***
Heinz Mauelshagen Sistina Software Inc.
Senior Consultant/Developer Am Sonnenhang 11
Mauelshagen at Sistina.com +49 2626 141200
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