Setting up Mirroring for failed mirror

Category: sql server mirroring

Question

doineedanid on Sun, 22 Nov 2015 23:03:33


For one of our environments, we used to have a DB mirrored to a different server. One of the reps changed the recovery model to Simple by disabling the mirroring to do certain activities during which the "principal" db was updated with more information. Now, I am unable to simply restore the mirroing as i get an exception saying that the db has rolled forward to a point in time. This is a very huge DB (around 1 TB). Now i guess the only option to get mirroring back on is to .. 

- Take FULL Backup of principal

- Take Transaction log of principal

- Restore FULL backup on mirrored site with NO RECOVERY

- Restore Transaction log on mirrioed site with NO Recovery

- Start Mirroring on Principal. 

Unfortunately, the FULL backup is taking around 20 hours during which inserts will happen as its an active DB. And pretty sure the restore os this DB on the mirroed site will also take 20 hours. So, almost 2 days. But how will mirroring succeed since the restored DB is now "old"

ex:

- Nov 22nd  @ 1am - FULL backup started on principal

- Nov 22nd @ 9 pm - FULL backup done

- Nov 22nd @ 9pm - transaction log backup pn principal

- Nov 23rd @ 1 am - Restore stars on Mirror site

- Nov 23rd @ 9 pm - FULL and transaction Restore with no recovery Done. 

At this point if I start Mirroring on Principal, will synchronization take in to affect. How will all the data from Nov 22nd @9pm to Nov 23rd @9 pm be synchronized. Do i have take another tlog back @ Nov 23rd  @ 9pm and restore it on mirror site after original tlog restore. 

Since the existing mirrror site had a DB can i just delete the DB on it before new restore ?

Replies

Praveen Rayan D'sa on Mon, 23 Nov 2015 04:49:06


Hi,

Take tlog backup post 23rd 9pm and restore it on mirror, this will synchronize your databases.

As per your second question is concerned, you can either overwrite the database on secondary server or you can drop it and create new db.