Hi,

While discussing some of the points with folks we just got in to a topic of Exchange DB recovery.

If i am running a Exchange 2007/2010 and if my Disk drive where DB is resided is crashed completely and do not have any backup. Now i am left with only transaction logs and not even have edb file. In this case will i be able to recover my old data using Transaction Log Files ?

I understand that new Blank DB can be created in new Drive if drive is crashed but my worry is for recovering the old mails.

I hope i wont be able to reply my old logs in newly created/black DB since sequence of log file is different.

Kindly share your experience/ thought on above case.

Note: Pls assume that no high availability or backup is in place, this we are thinking as last step of rec

Hi

It should be possible - might not be that easy.

You need to create a Recovery Storage Group, Restore the database where the mailbox is located to this RSg (the restore must be older than the e-mails you want to recover, restore the transaction logs that should contain the messages to the RSG and then replay all the logfiles.

The above procedure assumes that you do have the backups necessary to perform the operation

http://technet.microsoft.com/en-us/library/bb125218(EXCHG.80).aspx

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Hi Terence,

Thanks for your revert.

I understand that its possible if we have any DB backup and then replay the logs. Here we wanted check the possibility of replaying the log if DB/edb file is also not available.... is it possible to create blank DB and then replay the logs through some tools ?

As per my view its not possible to replay the logs of one DB in to other DBor newly created blank DB since log sequence will be different for each DB.

Hi
   What happens when the database file is lost? If we have all the log files still available it should be possible to retrieve all information. everything is logged in the log files, even the creation of database files
   If you dismount the database, delete the database file mailbox database.edb or whatever name you have given the database and try to mount the database again, the following error is raised:one of database file is missing. Mounting this store will force the creation of an empty database. When you click Yes a new mailbox will be created in the same location as the old database. This is a completely new database. Although it has the same name mailbox database.edb as in the previous step, it has new signatures. Recovery of old log files will not result in information being replayed into the database because it is another database in this scenario. And remember, since all information is logged into the log file the creation of this new database is also logged. Choose No, and then delete the checkpoint file E00.chk and try to mount the database again. No error message is raised and the database is mounted. Even better, when you log on to your test mailbox you will see that no information is lost either. Therefore it starts to recover all information by replaying the available log files.  It starts with the oldest log file E0000000001.log which also contains the creation of the initial database file. All information in the other log files is replayed into this database until it reaches the end of the last log file E00.log. The database is mounted and ready to use.When Exchange Server cannot find the database file but it does find the checkpoint file it will not replay the log files. It starts at the end of the last log file E00.log and it will create a new database.

If you have all of the log files (including 01.log) the database can be created. The event to create the .edb file lives in 01.log, so when ese replays the first log file, it'll create the .edb.

But who keeps all of the log files starting from day 1?

Right, even one months old successful full backup would truncate the initial log files - including (I suppose) the ones involved in the creation of the database.

Still an interesting hypothetical recovery scenario. 

If your all exchange database backup is being crashed , you can recover your exchange server database by using a software Kernel for Exchange recovery tool that recover all .edb files and data from exchange server.

Topic seems very interested. I read out the whole conversations and reached the conclusion that log files are not available (from beginning) to restore the old db database by creating new one. It is sent-percent sure that without initials log files, you can not restore or create old database inside newly created database file. Only 1 hope is left to get out old database if old edb files are available on crashed hard disk. Crashed hard disk can be successfully read by many data recovery tools (simply search on google) and these tools allow for extracting the hdd data. Once you get able to extract old database files, run and install an exchange edb file converter application that will extract the mailboxes into pst file format. PST file can be easily imported into exchange server (inside newly created db file) using exchange import function i.e. powershell script.

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