Hello there

As part of sql failover clustering I add storage disk to hold sql server
database

1. Does the storage area can be in Raid 5 for better perfomance and
availability?
2. If I set two storange areas at the same network can i use replication to
transfare data from main Storage area to second storage area so if the
storage ares goes down the second storage area will start working?

Roy,
Raid 5 is often used for the data files in databases. Raid 0+1 is used in
those cases where you want even better performance and have loads of disks.
Replication can be used as a DR solution and it's worth investigating the
differences between replication and log-shipping, which is usually considered
a superior technology for this purpose (and database mirroring also on SQL
Server 2005).
HTH,
Paul Ibison