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Understanding Exchange 2007 logs

Posted on 2011-03-04
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Hi

I'm trying to understand log files and Exchange 2007.

I understand the basic idea, but was hoping for some help with more concepts.

So if I look at a log folder, there are logs such as E01.log, E010001AED0A.log, E01res00001.jrs. There are also other logs such as E01.chk and E01restoreenv

Could someone explain what the E01.log actually does? From what I've read, it's the log file that actually being written to, but that doesn't make any sense to me.

The E01res00001.jrs is the reserve log to allow the store to dismount gracefully if space runs out, correct?

E01.chk is the Checkpoint file which keeps a note of which logs have been commited to the DB, correct?

And the E01.restoreenv file is the equivalent of the E01.chk but for restored database?

Am I thinking along the right lines?
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Question by:Joe_Budden
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Akhater earned 500 total points
ID: 35039251
e00.log is the file actually in use, when it becomes full (i.e. 1meg) it will be rename to e00xxxxxxx.log and a new e00.log is created

the jrs is just reserving space so, in case you run out of hdd space, exchange has enough space to gracefully shutdown

>>E01.chk is the Checkpoint file which keeps a note of which logs have been commited to the DB, correct?

almost correct although in exchange logs are not written then commited to the db, the 2 operations happen simultaneously


 E01.restoreenv is indeed used for restored databases
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by:Joe_Budden
ID: 35039309
Thanks for answering Akhater.

So, are you saying that for example, E01.log is the first log to be written, then that becomes E0100001.log, then E01.log is written to "again", after it's full, it becomes E01000002.log, and the E01.log is written to again etc?

As regards E01.restoreenv, are you saying that when I restore a recovery database, it is the E01.restoreenv file that tells the database which log files have already been written to? If I was to delete this file, then the recovered DB would attempt to replay ALL the log files?

Out of interest, I know when I restore a DB, I have to tell the backup software where to send the logs to a temp location. How does Exchange know this is the place to replay the logs?
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by:Akhater
ID: 35039347
>So, are you saying that for example, E01.log is the first log to be written, then that becomes E0100001.log, then E01.log is written to "again", after it's full, it becomes E01000002.log, and the E01.log is written to again etc?

yes but it is not written to "again" the e01.log gets renamed to E0100001.log and a new e01.log gets created


>>As regards E01.restoreenv, are you saying that when I restore a recovery database, it is the E01.restoreenv file that tells the database which log files have already been written to?

It contains which log file were restored

>> If I was to delete this file, then the recovered DB would attempt to replay ALL the log files?
no it won't work at all if i am not mistaken but don't quote me on this

>>Out of interest, I know when I restore a DB, I have to tell the backup software where to send the logs to a temp location. How does Exchange know this is the place to replay the logs?
also written in the restore.env file
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by:Joe_Budden
ID: 35046869
Thanks...

Before I close this one out, could you confirm/describe what the restore.env file does exactly? I'm still not sure about that one
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by:Akhater
ID: 35047026
read Important Values in the Restore.env File


http://support.microsoft.com/kb/253914
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