Resetting Exchange Transaction Log Numbering sequence

Posted on 2009-05-19
Last Modified: 2012-06-22

We are running Exchange 2003 SP2.

I have heard that the transaction log numbering sequence is limited to 1million.

The solution to this is to move all log files and checkpoint to another location.

My question is - what act actually resets the log sequence? Is it effectively deleting the checkpoint file so that the logs start from #1 again? What in layman's terms does the chk file do?
Question by:kam_uk
  • 3
  • 2
LVL 13

Expert Comment

ID: 24428405
What does the .chk file do?
The E##.chk file maintains the checkpoint for the Storage Group. The ## represents the Storage Group number with the First Storage Group file called E00.chk. This checkpoint file keeps track of the last committed transaction. If you are ever forced to perform a recovery, this file contains the point at which the replaying of transaction logs starts.
So ineffect the .chk file keeps track of the last transaction log that was committed to the database
What act actually resets the log sequence?
It is the combined process of moving both the log files as well as the .chk file that resets the log sequence
This MS article also talks about resetting the log sequence

Author Comment

ID: 24495218

So - if I moved the log files but not the chk file - would this cause database corruption?
LVL 13

Expert Comment

ID: 24499366
Not in all scenarios will it cause database corruption.....and one cannot be 100% sure.
The chk file keeps track of the last committed transaction log file and the point from where the log files should start the replay process.
The chk file is just like a pointer for transaction log replay.

Author Comment

ID: 24510244
Hi FearNoMore...

I was just thinking there would be database corruption because if the logs were moved manually but *not* the checkpoint file, then Exchange would be looking for logs that were no longer there? Whereas if the chk file was moved, then Exchange would essentially just start the log sequence from scratch?

LVL 13

Accepted Solution

FearNoMore earned 500 total points
ID: 24515091
Exchange would definitely look for the logs based on the chk file but if they are not present then it would generate an error and state that the log files could not be replayed since they were not found.
So in effect if the chk file is present and the log files have been moved manually, the database would definitely try to locate the log file that is referred by the chk file....but do remember that there is no actual log file replay taking place and hence there is no data being written into the database.
So since there is no data being written into the database, there is a low possibilty that the database would actually get corrupt.
But all in all, these are all process that are carried out internally by the Extensible Storage Engine (ESE) and hence we cannot be too sure that this will cause database corruption.
You should make sure that the chk file is also moved along with the other log files, to ensure that the log sequence is regenerated.
I hope this makes things clear

Featured Post

Does Powershell have you tied up in knots?

Managing Active Directory does not always have to be complicated.  If you are spending more time trying instead of doing, then it's time to look at something else. For nearly 20 years, AD admins around the world have used one tool for day-to-day AD management: Hyena. Discover why

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Suggested Solutions

Disabling the Directory Sync Service Account in Office 365 will stop directory synchronization from working.
This process describes the steps required to Import and Export data from and to .pst files using Exchange 2010. We can use these steps to export data from a user to a .pst file, import data back to the same or a different user, or even import data t…
To add imagery to an HTML email signature, you have two options available to you. You can either add a logo/image by embedding it directly into the signature or hosting it externally and linking to it. The vast majority of email clients display l…
This video discusses moving either the default database or any database to a new volume.

910 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question

Need Help in Real-Time?

Connect with top rated Experts

24 Experts available now in Live!

Get 1:1 Help Now