HP Proliant DL 380 G5 increasing server space

[Shaheen1]

Hi All

I have HP Proliant DL 380 G5 server running Symantec Back Exec. It has 2 x SAS 146gb drives and 2 x SAS 300gb configured as raid 5 with portions as C drive 58gb and E drive 351gb. We need to expand the server space for storage. Is it possible to use one of these options

1. Change the 2 x 146 gb SAS drives to 300 gb having 4 x 300gb SAS drives, possibly adding a 5^th drive for more storage if required, without reinstalling the OS on the server.
2. Add 2 compatible SATA drives with the current setup to created another drive for storage and to point Symantec staging for restores. This is the preferred option as SATA drives should be cheaper. Mixing SATA and SAS drives.
3. Move entire drives to SATA which would require minimum of 3 x SATA drives for raid 5. Least preferred as this would require OS re-install.

The Array controller is Smart Array P400 and the specs sheet for the server states that it can host SATA drives. I am also trying to find the latest compatible SATA drives for this server.