In a mirrored database system, mirror resynchronization of fixed length pages is optimized for quick repair and high availability by identifying those lost page changes that must be made for resynchronization and ignoring other duplicate changes. Essential pages are identified using log sequence numbers (LSNs) to locate the most current version of a changed page, and other lower valued LSNs of less current versions of that page are eliminated as having changes that are duplicated in the current version of the page. Page changes since the last database checkpoint before losing mirror synchronization and the current LSN of the transaction log are identified as possibly necessary changes to be made.