Exchange 2003 Transaction Logs

Just ran into an issue where the mail store would not mount.  Deleted the Tranaction Logs, Restarted Exchange Services, and the Store Mounted successfully with new transaction logs.  Is there a negative impact to doing this?  What are the short/long term affects, if any, when transaction logs are deleted.

(The original logs are backed up in case i have to revert back)
capitalcitycomputersAsked:
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Malli BoppeCommented:
You should never delete transaction logs.You should have run a incremental or a full exchange backup to purge the logs.When your exchange receives an email its not straight away written to database, its written to  transaction logs first and  some time later its written to exchange database.You would loose emails if these transaction logs were not written to the database.
More info about transaction logs
http://www.msexchange.org/articles/Transaction-Logs-Lifeblood-Exchange.html
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ConchCrawlCommented:
an excerpt from MS on removing log files manually:
If you remove a log that contains data that has not yet been written to the database files, the databases will no longer be mountable after an abnormal stop. Therefore, you must determine which logs are safe to remove before you manually remove any Exchange Server transaction log files.
In your case they must've already committed the data to exchange and were no longer needed :-). For future reference if you don't have a current backup of the transaction logs move them instead of deleting them so you can back them up or restore ones that you may need to mount the store.
Sometimes you have to do this but it is better to be safe than sorry.
Hope this helps.
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abhiyCommented:
I would say you were pretty lucky with that.
1st the reason why your store would have dismounted is that the log file directory drive would have run out of space.
2nd Once the log drive fills up the exchange application shuts down the stores bringing the database files into consistent state. A consistent database file would not require any log file. Hence after deletion of log files you were able to mount the stores.
(Incase the database would be inconsistent with even a single log file required, you would have regretted on your decision. Unable to retrieve the deleted log file would have cost you to either restore database from backup or  else to repair. Both are time consuming)

Following are few articles which you can refer for better maintainace of log files:

How to remove Exchange Server transaction log files
            http://support.microsoft.com/kb/240145

Transaction Logs, The Lifeblood of Exchange
            http://www.msexchange.org/articles/Transaction-Logs-Lifeblood-Exchange.html

Understanding the Exchange Information Store
            http://www.msexchange.org/articles/Understanding-Exchange-Information-Store.html
 
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hutnorCommented:
The logs can be used to restore lost data to your database after you have restored it from a backup.

With no logs you can not update the restored database & then you will have missing emails.

The logs are wiped after a full backup.

If you need to remove them yourself you should keep a copy of them somewhere until a full backup of exchange is made.
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kieran_bCommented:
If you are right out of space, a quick trick is to compress the oldest 95% (or so) of transaction logs - compress, not zip up - just select the oldest ones, right click, advanced, compress. They are text files so compress quite well.

Then, as stated, do a backup - the real issue with messing with transactions logs is that a) it is abundantly clear that your backup is inadequate (otherwise you wouldn't have log problems) and b) if your databases are even just a little unhappy with life, you now have unmountable stores AND weak backups.

Kieran
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capitalcitycomputersAuthor Commented:
Thanks for the feedback.  Everyone gets points
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