We had and sometimes are still having some issues with 9i R2 Data
Guard. One of the most annoying is the the fact that in the MAXIMIZE
AVAILABILITY mode a database is not checking if there are any archived
logs available and is crashing if there is any gap (even fetchable from
archived logs). That means that in most of the cases, restarted Data
Guard primary site will not start and the protection mode must be
changed to MAX PERFORMANCE to synchronize everything and then back. Why
in most of the cases Data Guard stanby got desynchronized even if
shutdown was done properly (i.e. shutdown immediate on primary and
cancel recovery + shutdown on standby) we have never learned.
Also some issues with RMAN, such as impossibility of using old RMAN
catalog after failover, are unconvenient.
Data Guard is also not reporting gaps consistently, so for DG it is
possible to become desynchronized with only one (not repeated) message
in the alert log, which could be easily overlooked. It is even worse,
because data dictionary view V$ARCHIVE_GAP may or may not report gaps
correctly (was verified by Oracle Support).
Overall impression from our Data Guard is that we are migrating to SRDF
in few months and no one will be missing DG when it will be gone.
--
Dusan Bolek
Received on Mon Feb 06 2006 - 00:43:26 CST
