In order for the DR system to be ready to jump in when a disaster happens, its database has to be up-to-date with the database of the LIVE system.

This is typically achieved by the replication jobs as explained in Step #2, Disable SQL Server jobs on DR-GN4SQL.

Depending on the frequency of transaction logs, the DR database may be a bit, or more than just a bit out-of-sync with the LIVE database. This is unavoidable.