26 May Oracle 12cR1 : ORA-16775 with Cascading Standby Databases
Finally I’m back at my English blog, I had been posting at Pythian’s blog and in my Spanish blog , but I had this one a little forgotten, but I promise to make a comeback at it.
Recently in my Spanish blog, I had written a blog post in where I configured a cascading Standby (Spanish), but while playing with it, I stumbled into an error when I had tried to do a switchover from the first Standby to the second Standby which I will try to explain in this blog post.
To give a bit of a background , I had a setup of 1 Primary Database and 2 Physical Standby’s with 2 farsync instances
These are the RedoRoutes for all 3 DBs and the 2 FarSync instances
So I have no problem doing a switchover from orcl to orclstby or orclrep, or as well when I had orclstby as a primary and do switchover to orcl
But the problem came when I tried to do a switchover from orclstby to orclrep, the error ORA-16775: ORA-16775 : target standby database in broker operation has potential data loss popped up.
While doing a revision of what logs had been applied to orclstby and orclrep, I saw now lag nor a redo log missing. Though I did see that there were a couple of logs pending on being shipped and applied which was weird.
If you remember the RedoRoutes for orclstby, I had the following:
Meaning that the local database (orclstby) should only be sending the logs to the farsync2 instance, and the farsync2 will be sending the redo to the orclrep database. Which would be this topology
So the problem that I saw and the way I solved it, was that revising the log_archive_dest_2 of orclstby which is the one defined for the orclrep DB, I saw that it was enabled as well as the log_archive_dest_3 which is the one for the farsync2 instance
So what I did, was DEFER the log_archive_dest_state_2 in orclstby
And now I was able to do the switchover from orclstby to orclrep without a problem
Right now I am assuming this is a bug for cascading databases with Dataguard in 12cR1, but I need to do a bit more research if it’s true or not, but in the meantime I hope this helps 🙂