vgcreate and vgextend dont use the maximum space on PV

[Bernd Broermann <bernd@broermann.com>]

Hello ,

I try to migrate mirror an LogicalVolumes from one disk to the other.
The disks are identical.

/dev/emcpowerd     52313  myvg
/dev/emcpowereh    52313

emcpowerd shows 512K unusable.

rhel6.3# pvdisplay /dev/emcpowerd
   --- Physical volume ---
   PV Name               /dev/emcpowerd
   VG Name               myvg
   PV Size               51,09 GiB / not usable 512,00 KiB
   Allocatable           yes (but full)
   PE Size               4,00 MiB
   Total PE              13078
   Free PE               0
   Allocated PE          13078
   PV UUID               GyMBL2-v84W-719F-069j-Mga6-6tSe-c9fP2D

when extending ( even creating ) the VG, the new PV show one less PE and 
4,5 MiB .
rhel6.3# vgextend myvg /dev/emcpowereh

rhel6.3# pvdisplay /dev/emcpowereh
   --- Physical volume ---
   PV Name               /dev/emcpowereh
   VG Name               myvg
   PV Size               51,09 GiB / not usable 4,50 MiB
   Allocatable           yes
   PE Size               4,00 MiB
   Total PE              13077
   Free PE               13077
   Allocated PE          0
   PV UUID               p6VT4i-Q98Y-MbfP-WHFi-V01B-Ohcy-yRv83D


So 13077 PE are less then 13878 PEs and mirroring fails.
Note: the emcpower devices are SAN Devices and /dev/emcpowerd was  
created under RHEL5

How can I allocate the full disk ?

Thank you
Bernd

Linux rhel6.3  2.6.32-279.11.1.el6.x86_64 #1 SMP Sat Sep 22 07:10:26 EDT 
2012 x86_64 x86_64 x86_64 GNU/Linux
lvm2-2.02.95-10.el6.x86_64