I have a pair of SQL Server 2008 R2 servers hosting a synchronously mirrored database with no witness. This weekend, we had to do some network maintenance so I paused the mirroring. Upon resuming, the principal's status reverted to the usual Principal, Synchronized. The mirror, however, now reads Mirror, Synchronized / Restoring... I don't recall the Restoring... part usually being there.
The transaction log has begun to grow on the principal, as well, despite hourly log backups. This suggests to me that the synchronization process isn't freeing up transaction log space.
What's going on here and how do I fix it?