Sybase Mirror Activator

Sybase Mirror Activator introduces a transaction-based dimension to existing block-based data mirroring platforms. As a result, Sybase claims that their system can reduce bandwidth requirements by up to 50%, while additionally providing certain transaction replication-based benefits such as a standby DB that is availabile for queries.

Block-based replication seeks to duplicate the information in the database to remote hardware synchronously at the disk block level, providing instant failover support via the always-ready "hot standby" replicated database. Transactional replication, however, is asynchronous in nature; in that it seeks to replicate data in the remote database by examining and reapplying the actual transactions that were applied to the original DB.

Sybase Mirror Activator works in conjunction with existing block-based mechanisms. Instead of synchronously replicating the entire database, however, Sybase allows these block-replication platforms to sychronously replicate only the transaction log of the database; with Sybase Mirror Activator then applying the transactions to the replicated database at the remote location from the mirrored logs. The result, according to Sybase, is a combination of benefits from both methodologies: DB log information is replicated synchronously and thus the remote site receives the necessary transactions in syncronization with the live server; while transactional-based application of the changes to the remote DB enhances protects against disk corruption from the live server. Also, if not configured for disaster recovery mode, the replicated database is available for standard, live query and viewing applications and needn't be completely idle until a disaster occurs.

Because only the log information is block-replicated to the remote site and not the full contents of the DB, Sybase states that Sybase Mirror Activator is able to reduce network bandwidth requirements by up to 50%. Supported mirroring technologies (for the replication of the log) noted by the vendor include EMC's Symmetrix Remote Data Facility; IBM PPRC; Hitachi TrueCopy; Veritas Volume Replicator; and Network Appliance SnapMirror.

Sybase Mirror Activator is available for Sybase ASE and now Oracle. Contact Sybase for further information.