Can you safely log ship between primary and secondary servers on different cumulative update versions?
emmalee last edited by
Need to update primary from 2019-CU14 to 2019 CU15 and a few hours/days later update secondary to CU 15 once the primary is deemed stable. Can you safely log ship between primary and secondary servers on different cumulative update versions (CU-15 to CU-14 in this case)?
You can see Microsoft recommendations on the https://docs.microsoft.com/en-us/sql/database-engine/log-shipping/upgrading-log-shipping-to-sql-server-2016-transact-sql?view=sql-server-ver15 doc:
To preserve your log shipping disaster recovery solution, upgrade, or apply servicing updates in the appropriate order. Servicing updates include service packs or cumulative updates.
The doc gives some specific info related to the upgrade and the order is the opposite of the one you intend to apply the update on your environment:
The upgrade process involves upgrading the secondary server instances of SQL Server before upgrading the primary server instance. Always upgrade the secondary SQL Server instances first. Log shipping continues throughout the upgrade process because the upgraded secondary server instances continue to restore the log backups from primary server instance. If the primary server instance is upgraded before the secondary server instance, log shipping will fail because a backup created on a newer version of SQL Server cannot be restored on an older version of SQL Server. You can upgrade the secondary instances simultaneously or serially, but all secondary instance must be upgraded before the primary instance is upgraded to avoid a log shipping failure.