Removing physical disk from RAID & LVM

Hi,

I have filesystem build up with 5 x 320 GB disks with identical
partitions. Disks have 2 partitions and the first one is dedicated for
RAID-1 (/dev/md0) and second one is dedicated for RAID-5 (/dev/md1). The
disk /dev/md0 is mounted as /boot and the /dev/md1 is prepared for LVM.
PE size is 32 MiB and there is 38035 PEs.

I am going to remove one 320 GB disk and have already reduced the sizes
of existing LV:s. 1) What is the sufficient free PE number before I can
imagine shrinking of RAID-5 device? 2) How should I procede after having
enough free PE:s?


Tero