We have a Oracle 9i database with ~300GB of data, some large tables
(5+ million rows). There are a few stored procedures and triggers, and
some sequences. Nothing super "Oracle". Applications connect with a
combo of ADO, ODBC, and SQL Plus.

Currently use standby server setup with replication.

We are thinking about converting the entire thing to mySQL 5 with a
cluster setup or Oracle 9i enterprise with shared SAN for fail-over.

Looking for specific comparison between the 2 and issus to look out
for during a conversion? Please do not reference mySQL 4.x which does
not have clusters, triggers, etc. We want a detailed, expereinced
answer from someone understanding that open source can be used in the
enterprise when supported well.