Understanding .TUF file in log shipping | SansSQL

Wednesday, June 20, 2012

Understanding .TUF file in log shipping

I am very happy and excited to be part of Sans SQL with this being my first contribution here. So without wasting much time let us get on...

What is .TUF file? What is the significance of the same? Any implications if the file is deleted?

.TUF file is the Transaction Undo File, which is created when performing log shipping to a server in Standby mode.
When the database is in Standby mode the database recovery happens when the log is restored; and this mode also creates a file on destination server with .TUF extension which is the transaction undo file.

This file contains information on all modifications performed at the time backup is taken.

The file plays a important role in Standby mode... the reason being very obvious while restoring the log backup all uncommitted transactions are recorded to the undo file with only committed transactions written to disk which enables the users to read the database. So when we restore next transaction log backup; SQL Server will fetch all the uncommitted transactions from undo file and check with the new transaction log backup whether committed or not.

If found to be committed the transactions will be written to disk else it will be stored in undo file until it gets committed or rolled back.

So... that's it for now! Happy Reading!!


sita said...

nice explaination

Rahul said...


Vijay Reddy said...

when log shipping initiated tuf file will be created ...next ( .wrk) folder file will be creates....finally it has converts as ( .trn) file
so..i am confusing here....when it commits....in tuf file..it wud be chnaged as .trn file..?

Sandeep Diwakar said...

Explained in excellent manner

Unknown said...

Why tuf file will create..?

Vijay J said...

Hi -
I have a log shipped database which failed due o disk space issue. I removed the log shipping from both secondary and primary servers. But the TUF file remained there and not letting me re-create log shipping. It thinks database is still there. And I won't let me delete TUF file saying it's in use. How to get rid of this TUF file so I can re-create log shipping?


Unknown said...

Awesome Explanation.

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