Increase RAID1 Array
 

i am trying to increase raid1 arraysize whcih is predefind,
what i did i add two more drive in the raid but i could not increase raid array

exp:-
Creation Time : Wed Feb 2 18:14:56 2011
Raid Level : raid1
Array Size : 104320 (101.89 MiB 106.82 MB)
Used Dev Size : 104320 (101.89 MiB 106.82 MB)
Raid Devices : 4
Total Devices : 4
while in above case i have added two more drive but array size is same
Now how i can increse array ????

pls give detail commands
thanks in advance
atulya

perhaps make a fake software raid(LVM?) or perhaps btrfs