Exchange 2007 Transaction Logs

Hello,
I am curious about Exchange Server transaction logs and I believe I have an understanding how they work and they are designed to enhance performance on the Exchange Server. How often does Exchange update the priv.edb file with the transaction log information, and how can I force the transaction log data to be updated to the priv.edb file other than through backup?
Thanks,
John
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jhiebAsked:
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shauncroucherCommented:
It is updated at the same time the log file is updated. It does not write to log first and then db, it does both syncronously.

You say Exchange 2007, then talk of priv1.edb? Exchange 2007 is "mailbox database.edb"

Backup simply flushes the logs.

Shaun
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jhiebAuthor Commented:
Sure, I still consider the edb file the same but I will make note of the differences. I don't see how the data is written tot he log and the edb file syncronously. If that was the case then why have a transaction log file? I thought the purpose was to keep Exchange from lagging because of the potential high demand on the EDB.

If I simply copy the EDB file from the Exchange environment isn't it possible that transactions are still in the log file and not in the EDB file?

I guess that leads to my last question. I migh have to create another post for this so let me know. Eventually, I want to know if it is possible to recover data from a transaction log even if the Exchange server does not exist anymore and the backup is fried.
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shauncroucherCommented:
why have a transaction log file?

This is for circumstances where the database is corrupt but the transaction log files are available and you have a good last backup. You don't loose so much data. Remember, log files should be on seperate LUN's to the DB.

lagging because of the potential high demand on the EDB.

Not with 2007, I/O is nowhere near as intensive.

isn't it possible that transactions are still in the log file and not in the EDB file?

Not if the database is in a clean shutdown state no (you dismount it properly for instance).

recover data from a transaction log even if the Exchange server does not exist anymore and the backup is fried

No you can't do that.


Shaun
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AkhaterCommented:
Exchange has "in memory" DB , the edb file and the log files

every transaction is written simultaneously to the in-memory db and the log files

it is later committed from the memory to the edb file and NOT from the log files as many think

the log files are just in case a crash happens before the transaction is written from memory to the edb file.

to answer your other question if you dismount a database then everything in memory will be committed and no you will not need log files
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