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SQL Anywhere 10.0.1 » SQL Remote » SQL Remote Administration » Running the Message Agent

Connections used by the Message Agent Next Page

Replication system recovery procedures

SQL Remote replication places new requirements on data recovery practices at consolidated database sites. Standard backup and recovery procedures enable recovery of data from system or media failure. In a replication installation, even if such recovery is achieved, the recovered database can be out of synch with remote databases. This can require a complete resynchronization of remote databases, which can be a formidable task if the installation involves large numbers of databases.

In short, recovery of the consolidated database from a failure at the consolidated site is only part of the task of recovering the entire replication installation.

Protection of the replication system against media failures has two aspects:

Replicating only backed-up transactions

By default, the Message Agent processes all committed transactions. When the Message Agent is run with the -u option, only transactions that have been backed up by the database backup commands are processed.

Transaction log backup is carried out using Sybase Central or the dbbackup utility, or off-line copying and renaming of the log file.

By sending only backed-up transactions, the replication installation is protected against media failure on the transaction log. Maintaining a mirrored transaction log also accomplishes this goal.

The -u option provides additional protection against total site failure, if backups are carried out to another site.