SQL Server AlwaysOn AG Automatic initialization (11)

When not to use automatic seeding

In some cases, automatic seeding may not be the best choice for initializing secondary replicas. During automatic seeding, SQL Server performs a backup over the network for initialization. This process can be slow if the database is very large or the secondary replica is a remote copy. The transaction logs for these databases cannot be truncated during the backup process, so if the busy database initialization process takes a lengthy time, the transaction log may increase significantly. Before you add a database to an availability group with automatic seeding, evaluate the database size, load, and site distance between replicas.

SQL Server AlwaysOn AG Automatic initialization (11)