TUF File in LogShipping...

What it TUF file?

>>TUF stands for ->T ->Transaction  U->Undo  F->File  so it is Transaction Undo file.

Explanation:-

When restoring transaction log with the “STAND BY” option, SQL Server will go over the transaction log and save all uncommitted transactions to a file with .tuf(Transaction UNDO File) extension.

example:- let us assume a rebuild index on a big table that has run for 45 mins and let’s say 3 log backups were taken in this duration, so first log backup uncommitted transactions will be written to tuf file while restoration and when the second log backup is being restored, the sql server will redo all the uncommitted transactions from the tuf file and will continue the restoring  the log backup but the second log backup also has uncommitted transactions so SQL server will again UNDO the index operation and will save the uncommitted transactions to tuf file and this process continues until transaction is committed in further log backups causing the delay in LOG RESTORE…

Q)My Tuf file deleted unfortunate when the server was shutdown or during the server down time then what will happens to the log shipping?

>>The log shipping will not work.

Reverse Log Shipping process

REVERSE LOG SHIPPING

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1.Disable the log shipping backup job on the primary server.
2.On the standby server, run the log shipping copy and restore jobs to restore any remaining transaction log backups.
3.Disable the log shipping copy and restore jobs on the secondary server.
4.On the primary server, create on last transaction log backup using the NO RECOVERY option.
5.On the standby server, restore this transaction log backup using the RECOVERY option.
6.On the standby server (which will now be the primary server), right click on the database and select Properties -> Transaction Log Shipping.  Enable the database to become the primary database and configure the backup and secondary server settings.