Hi Mahes,

just few thoughts:


>>     1. With the RAID 5 at AIX level, should a second, synchronized  copy
     of DB volumes is required.

It had been argumented on this forum that TSM mirroring has 
some advantages over OS-based Raid system.
Anyway, an OS-based RAID and only single database volumes
would definitely help against single disk failure as well.

>>      2. If I do not keep a second copy and take daily full backup, would
it
     be RISKY.
Database backup is mandatory whether you use Raid5 of whatever else.
I, for example, make full backupo each day and about 10 incremental backups
in between.

Be sure you can perform database restore - do test it!
be sure you can afford this down time in case of need.

>>      IBM's version is that since a second copy MUST be kept
It´s new for me. I think it is only recommended.

Raid 5 and 80 GB Database: do not forget, database updates (such as restore
from backup) will take much longer with Raid5!

regards
juraj salak