How to use lvconvert with two disks for mirroring? - Insufficient suitable allocatable extents

[root@MACHINE ~]# pvs -v --segments | head -1
Scanning for physical volume names
PV VG Fmt Attr PSize PFree Start SSize LV Start Type PE Ranges

[root@MACHINE ~]# pvs -v --segments | grep archivvg6
Scanning for physical volume names
/dev/mpath/orau11db6_32gcc1 archivvg6 lvm2 a-- 32.00G 32.00G 0 8191 0 free

/dev/mpath/orau11db6_32gcc2 archivvg6 lvm2 a-- 32.00G 0 0 8191 orau011archlv 0 linear /dev/mpath/orau11db6_32gcc2:0-8190

/dev/mpath/orau11db6_8gcc1 archivvg6 lvm2 a-- 8.00G 8.00G 0 2047 0 free

/dev/mpath/orau11db6_8gcc2 archivvg6 lvm2 a-- 8.00G 0 0 2047 orau011archlv 8191 linear /dev/mpath/orau11db6_8gcc2:0-2046

[root@MACHINE ~]# lvs | grep archivvg6
orau011archlv archivvg6 -wi-ao 39.99G

[root@MACHINE ~]# lvconvert -i 5 --mirrorlog mirrored -m 1 archivvg6/orau011archlv /dev/mpath/orau11db6_32gcc1 /dev/mpath/orau11db6_8gcc1
Insufficient suitable allocatable extents for logical volume : 10238 more required
Unable to allocate extents for mirror(s).
[root@MACHINE ~]# cat /etc/issue
Red Hat Enterprise Linux Server release 5.9 (Tikanga)

How can I update the orau011archlv to be mirrored? With 1 disk and 1 for mirror I can probably do it, but we have 2 disks + 2 disks for mirror.

How can I tell lvconvert command to use the 2 disks above as mirror?

Many thanks.