XADM: How to Recover When the Transaction Log Drive Fails

This article describes the steps to recover when the drive containing the information store or directory service transaction log files fails because of hardware problems.

Information Store Transaction Logs Lost

Following are the steps if the drive containing the information store transaction log files is damaged and all data is lost. These steps assume that the database files are on a separate drive from the transaction log files.

1. In Control Panel, Services, set the Exchange Server System Attendant service to Disabled to prevent it from starting up.
2. Replace the faulty drive with a new drive.
3. Create a logical drive with the same name as before and format it.
4. Recreate the Exchsrvr\Mdbdata directory on the new drive.
5. Backup the Priv.edb and Pub.edb on the database drive.
6. Restore the last online backup of the information store.
7. In Control Panel, Services, enable the System Attendant service.
8. Start the Microsoft Exchange Server Services.

At this stage, the information store will start, and will only contain data up to the time of the last backup, because the transaction logs containing the data generated since the last backup have been lost.

Recovering Data Generated Since the Last Online Backup

In order to try and extract data from the Priv.edb and Pub.edb files present at the time of the failure, use the following steps.

NOTE: The steps below may or may not work, depending on the state of the database files.

1. Install Exchange Server on a recovery server with the same Organization and Site names as the production server.
2. Create a new site, and DO NOT join the existing site.
3. Move out all files from the Exchsrvr\Mdbdata directory.
4. Copy the Priv.edb and Pub.edb files saved from the production server.
5. Repair the databases if necessary, and start the information store.
6. Run the DS/IS consistency adjuster
7. Run ExMerge.exe to merge all data between the last backup and the time of the failure, from the recovery server into the production server.

ExMerge.exe (Microsoft Exchange Mailbox Merge Program) is available on the Microsoft BackOffice Resource Kit, Second Edition, as well as from Microsoft Product Support Services.

Directory Service Transaction Logs Lost

Following are the steps if the drive containing the directory service transaction log files is damaged beyond recovery. These steps assume that the database files are on a separate drive from the transaction log files.

1. In Control Panel, Services, set the Microsoft Exchange System Attendant service to Disabled to prevent it from starting up.
2. Replace the faulty drive with a new drive.
3. Create a logical drive with the same name as before and format it.
4. Recreate the Exchsrvr\Dsadata directory.
5. Backup Dir.edb on the database drive.
6. Restore the last online backup of the directory service.
7. In Control Panel, Services, enable the System Attendant service.
8. Start the Microsoft Exchange Services.

Once the directory service starts up, it will contact the other servers in the site, and backfill any data generated since the last backup.