2012-02-25.


[For several years there's been no trouble; each (Gentoo) system 
has just found the lvm partitions on boot, and got the logical
devices available before the init scripts try to mount them from 
the fstab.  Now a recent Gentoo with 3.[12].x kernels has had 
trouble -- device nodes appear but aren't activated even by 
vginit -a ly. ]


How it was forced to work.

study:   /lib64/rcscripts/addons/lvm-start.sh
Avoid running this.

Hot-plug the relevant sata disk, if boot-time automation is a 
possible cause of the failures (two attempts at same thing?).


# vgscan    
get a list of the available physical volumes

# vgscan --mknodes   
( perhaps not needed? )

# vginit -a ly  
activate: 'yes'

Then find your devices under /dev/mapper/ .