good question...

that was exactly why we went with mirroring.

SQL Server Mirroring automatically copies the transaction logs from your source to the target.

the logs are backed up as part of normal OLTP operations and the copying of the logs from the OLTP server to a "Staging" Server has zero impact to the OLTP.

Once the logs are copied to the staging server, the staging server does the work to move the data (ETL) to the reporting system.

This is how we do it without impacting the OLTP.

The article shows a picture and provides the details.

If you have more questions, please feel free to contact me directly. Contact info is provided in my profile.

GAJ