Abstract: A method and apparatus for mirroring data between a plurality of sites is provided. At a first site of the plurality of sites, a record is maintained that identifies which changes made to one or more data blocks that are stored at the first site have had associated redo information replicated to the other sites of the plurality of sites. A priority value associated with a transaction that is to be performed at the first site is determined. The transaction specifies a modification to a data block. Thereafter, if the priority value indicates that the transaction should not be lost if the first site becomes inoperable, then the transaction is committed only after the record indicates that all other changes that have updated the data block at the first site have had their respective redo information replicated to the other sites of the plurality of sites.

Abstract: A method and apparatus for mirroring data between a plurality of sites is provided. A replication relationship is established between the plurality of sites that include a first site and a second site. A first database server at the first site receives an indication that a write operation could not be successfully mirrored at the second site. In response to the indication, the first database server initiates a membership voting operation by communicating with a quorum device to determine whether the first database server or a second database server associated with the second site should be removed from the replication membership. If it is determined that the second database server associated with the second site should be removed from the replication membership, then the first database server sends a message to indicate that write operations are no longer to be replicated at the second site.