unrecoverable_change is from v$datafile, which is from controlfile, not from datafile header.
if you refresh controlfile at standby, this all the information at standby v$datafile is incorrect.
It is very hard to detect. in a complex production environment.
enable force_logging in 9i is a good idea for standby
On 11/16/05, Bobak, Mark <Mark.Bobak@(protected)> wrote: > Josh, > > I'm not a standby or DataGuard expert, but, think about what the > unrecoverable change # represents. It's the SCN at which the last > unrecoverable operation occurred on that datafile. So, if the primary is > ahead of the standby, that means there are operations which have occurred on > the primary which did not propogate to the standby. This is a corruption > waiting to happen. If you activate the standby and a datablock is accessed > that was loaded unrecoverable on the primary, you'll encounter an ORA-26040 (See ORA-26040.ora-code.com). > > So, I assume (don't have a standby setup handy to confirm it) that the > default safe position is that they are equal, since, when you clone from the > primary to initially create the standby, they'd (presumably) be equal. At > that point, the only way for them to get out of sync is if you do an > unrecoverable (aka nologging) load in the primary database. > > Corrections welcome from those with actual DG and standby experience! ;-) > > Hope that helps, > > -Mark > > PS Note that in 9i (can't remember if it was 9.0.1 or 9.2.0 intorduction) > you can do ALTER DATABASE FORCE_LOGGING=TRUE; and everything will log, even > if people try to do nologging loads. > __ ____ ____ ____ ____ ____ ____ > From: oracle-l-bounce@(protected) [mailto:oracle-l-bounce@(protected)] > On Behalf Of Josh Collier > Sent: Tuesday, November 15, 2005 4:52 PM > To: oracle-l@(protected) > Subject: standbys and unrecoverable operations > > > Greetings, > > The Oracle documentation says that if the unrecoverable_change# for a > datafile reported (v$datafile) by the primary is greater than that reported > by the standby then you will need to recover that datafile (by copying it > over from the primary) in order to avoid block corruption errors if the > standby is activated. > > Does this also hold if the unrecoverable_change# are identical? > > have a good day, > > Josh C.
