I have received this warning on our corporate Exchange server, and im planning to rectify this according to http://technet.microsoft.com/en-us/library/aa998701(loband).aspxHowever, im worried about the fact we are now re-using transaction log file names, and our ability to recover. Specifically, this part of the above article: After performing the procedure below, all previous backups will be invalidated. This does not mean that the backups cannot be restored. However, the backups can no longer be rolled forward with additional transaction logs. If you must restore a previous backup after you remove the transaction logs, you will be able to restore data only up to the time that the new log generation was created. What happens if i want to restore data from say, 4 years ago, and we've already used the transaction file name again? Perhaps i need to sharpen my knowledge about how Exchange backups worth in depth. When transaction logs are 'commited' to the Exchange database, does this mean at recovery the transaction log files are no longer required? When are transaction log files required? My understanding was that transaction log files contain mail items received since the last full backup, and were only needed to 'replay' emails received since the last full backup.Cheers!

Gbug, You dont have to worry about the backup. Transaction log names are by design and once it ran out, you can always reset it by moving all the logs from the logs folder. and then mounting the database. In case something happens to your database in that case you need to restore the database to RSG and database will look for necessary logs and play only those log files. So you dont have to worry about the new sequence of log files. But make sure that you regularly do full backup of your exchange servers. Vinod |CCNA|MCSE 2003 +Messaging|MCTS|ITIL V3|

As Vinod has mentioned you do not need to worry about the Transaction logs, Just make sure that you regularly run full backups. For more info on what log files are, i would suggest you read the following article.. http://www.msexchange.org/articles/Transaction-Logs-Lifeblood-Exchange.html Hope that helps........ ------------------ Mukesh Parmar

Also take a look at this from the Exchange team. http://msexchangeteam.com/archive/2008/07/23/449339.aspx Mark Morowczynski|MCT| MCSE 2003:Messaging, Security|MCITP:ES, SA,EA|MCTS:Windows Mobile Admin|Security+|http://almostdailytech.com

Thanks for the replies. I am at ease about making this change, but id like to understand how it all hangs together. Specifically about how backups/restores work with Exchange.When a restore of a mailstore is executed into an RSG, are the backed up databases restored, or are the transaction logs restored, and then replayed? Do transaction logs ever get restored, or because the are being 'commited', does this mean they no longer exist, and the database is the only place to restore your mail from?Cheers.

HI, I am assuming you are using Exchange 2007. RSG has been comes with exchange 2003 Sp1.That will allow us to restore single mailbox or a single mailbox item of user using simplest backup program using Ntbackup.When you restore your Backup to a RSG will restore uncommitted logs also. Use below resource article to get understands how RSG works. if you have restore transaction logs you have ability to restore your database in point of time of failure. Normally Database and Logs directory place at two different drives and transaction logs need to backup several times per day such as 3 times a day and the run and full backup 1 time per day.In disaster situation you can restore last full backups and then restore transaction logsResourcesUsing Recovery Storage Group in Exchange 2007RegardsChinthaka

I'm using Exchange 2003.What im trying to get at, how does Exchange use backups to restore data.Does it restore the database, or does it restore transaction log files?

It depends on which type of backup you took. If you are restoring Full backup then it edb/stm file and set of committed transaction log for verification but if you are restoring Incremental Backup then it restore edb/stm file from full backup and then transaction logs from all incremental backup sets. So best practice is to take full backup after transaction logsequencereset. I guess, this should be mentioned in article also. Now come to main point, - If you want to restore some data prior to log sequence reset, you need to restore in RSG and it will restore edb/stm file and all the transaction logs generated prior to reset. - If you want to restore some data after log sequence reset, then you need to restore it from the backup taken after reset (which will be containing data which is sum of all since it is full backup taken after reset). Amit Tank | MVP Exchange Server | MCITP: EMA | MCSA: M | http://ExchangeShare.WordPress.com

Now come to main point, - If you want to restore some data prior to log sequence reset, you need to restore in RSG and it will restore edb/stm file and all the transaction logs generated prior to reset. - If you want to restore some data after log sequence reset, then you need to restore it from the backup taken after reset (which will be containing data which is sum of all since it is full backup taken after reset). Amit Tank | MVP Exchange Server | MCITP: EMA | MCSA: M | http://ExchangeShare.WordPress.com Ok, im still not 100%.When restoring to an RSG prior to log sequence reset, and i'm restoring from a FULL exchange backup, will it need to use transaction logs? I thought the logs were commited at backup, and were no longer required?