Mirror ReAttach for 2008R2 ???

Question

How do we re-attach the mirror to its principal after it's been detached for a while ?

Originally the mirror was restoring successfully. We broke the mirror manually, left it for a few days. 

Now we want to put the mirror back in place but without re-creating the mirror by restoring the latest backup of principal datafile and log .

Is it possible to do it ?

Answer 1

Hi,

Once you break the mirror SQL does not send or store the log records that are required to be sent from the principal to the mirror. Therefore the mirror cannot re-sync with the principal using the logs as they no longer exist. In theory if you had all the log backups you could roll the mirror forward to the current time however depending on how long it has been this is normally more hassle than it is worth.

If you did not break the mirror and were not syncing for a long period of time the transaction log on the principal would continue to grow larger as the log backups would not be able to recycle and wrap around the log as SQL would be locking those entries waiting to send them to the mirror.

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Sean Massey | Consultant, iUNITE

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Answer 2

Sean has a point... What you need to do is roll forward the DB using all transaction log backups that were taken since the mirror disconnect. If you can achieve this you can reestablish the mirror. Otherwise there is no way to do it unfortunately.

Answer 3

You must replay all log backups on mirroring since then before re-establish mirroing other wise you must recrease mirroring from scratch

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