Planning Migrations with Online Systems

Typically, migration is performed after configuring and running new collection. Depending on the amount of data migrated, the process may take hours or days.

Alarm and event migration can take a significant amount of time. You can mitigate the risk of data loss by configuring the alarm collectors before starting the migration. You may also choose to migrate your alarm and event data in blocks of time ranges.

If you are migrating Classic Historian data and decide to select the Overwrite Existing Tags option in the Migration Options dialog box, the existing Historian tag properties are replaced by the migrated Classic Historian tag properties and some configuration properties are overwritten. If you decide to clear the Overwrite Existing Tags option, tag information will not migrate into the Historian tag database. If you are migrating your Historian data into an existing Historian tag database, you may discover that tags with the same name exist in both the Historian database and the iFIX or Advanced Historian database.

If you are migrating Advanced Historian data and decide to select the Allow Updates to Existing Data option in the Advanced Historian to Historian Migration Utility, the existing Historian tag data will be replaced by migrated Advanced Historian tag data if the data points have the same timestamps. If you decide to clear the Allow Updates to Existing Data option, the data will not be migrated (replaced) where there is existing data with duplicate timestamps in Historian.