LVM: how to avoid scanning all devices

["Steve Keller" <keller.steve@gmx.de>]

When calling LVM commands it seems they all scan all disks for
physical volumes.  This is annoying because it spins up all disks that
are currently idle and causes long delays to wait for these disks to
come up.  Also, I don't understand why LVM commands scan the disks so
often since the information is in /etc/lvm already.  For example a
command like vgdisplay vg0 where vg0 is actively used and on a disk
that is up and running still causes a long delay because it scans all
my devices for other volumes although this is completely unneeded.

IMO only an explicit call to vgscan should scan for and update all LVM
information.

Steve