Problem with migrating from AIX 5.1 to 5.3

I'am migrating from AIX 5.1 to 5.3 during migration installation a receive message enough space for dir /usr.
My question is : how i can resolve this problem ? i can't reboot my server i hope that there is a command to obtain a spece without go out from installation procedure pannel...
I'am using migration method ..

Thanks in advance for you help