ASM Migration to New SAN

 Hi all,

One of our client have implemented their system on a Two Node Oracle 10g R2 RAC on HP-UX v2 env. and the Database is on ASM on HP EVA 4000 SAN.  The database size is nearly 1 TB.

Currently they have the following Diskgroup:

Diskgroup Name: 

DATA_DISK:

Disks:

DATA_DISK0000 - 1024 GB

DATA_DISK0001 - 200 GB

I want to know what would be the ideal size of the new Disks. As the Database is nearly 1 TB, can I create 60 Disks of 25 GB size [60 LUNs]?

Also is it possible for me to calculate how much time the rebalance would take to complete after adding the new disks and also how much time the rebalance would take to complete after dropping the disks. I am aware that we can also do one rebalance activity by adding new disks and dropping old disks at the same time. But is it ok to do that on Production env?