The HP NonStop TMF transaction manager is the foundation for building fault-tolerant and disaster-tolerant applications on HP NonStop servers.
For applications that are TMF-enabled, TMF guarantees the consistency and the correctness of the Enscribe and NonStop SQL databases maintained by the applications.
It accomplishes this ability by ensuring that either all of the operations included in the application’s transactions are applied to the database, or none are. Transactions are durable, surviving any fault in a NonStop server, by safe-storing all changes to the database in a mirrored, diskbased audit trail. The TMF audit trail is the heart of TMF.
An application is not informed of the completion of a transaction until its changes have been safe-stored in the audit trail. After a system recovers from a failure, the audit trail’s contents are used to roll back any incomplete transactions. The audit trail can be used to restore files that have been corrupted or that have been accidentally deleted. TMF allows databases to be reorganized online.
Backups can be written to physical or virtual tape without application downtime. Archived audit trails can be accessed to restore corrupted or deleted files while the system is fully operational.
Because transaction durability is guaranteed by the audit trail, the actual data in the databases does not have to be written to disk immediately. Instead, updated data blocks can be batched and written to disk at the convenience of the operating system. Thus, application processing capacity and response times are significantly enhanced by TMF. TMF provides an interface which allows it to support the management of transactions distributed across a heterogeneous network of other systems.
As will be described in upcoming sections, the TMF audit trail plays a key role in many of the HP NonStop data replication facilities. It provides a log of all database changes to be replicated to other systems.
For applications that are TMF-enabled, TMF guarantees the consistency and the correctness of the Enscribe and NonStop SQL databases maintained by the applications.
It accomplishes this ability by ensuring that either all of the operations included in the application’s transactions are applied to the database, or none are. Transactions are durable, surviving any fault in a NonStop server, by safe-storing all changes to the database in a mirrored, diskbased audit trail. The TMF audit trail is the heart of TMF.
An application is not informed of the completion of a transaction until its changes have been safe-stored in the audit trail. After a system recovers from a failure, the audit trail’s contents are used to roll back any incomplete transactions. The audit trail can be used to restore files that have been corrupted or that have been accidentally deleted. TMF allows databases to be reorganized online.
Backups can be written to physical or virtual tape without application downtime. Archived audit trails can be accessed to restore corrupted or deleted files while the system is fully operational.
Because transaction durability is guaranteed by the audit trail, the actual data in the databases does not have to be written to disk immediately. Instead, updated data blocks can be batched and written to disk at the convenience of the operating system. Thus, application processing capacity and response times are significantly enhanced by TMF. TMF provides an interface which allows it to support the management of transactions distributed across a heterogeneous network of other systems.
As will be described in upcoming sections, the TMF audit trail plays a key role in many of the HP NonStop data replication facilities. It provides a log of all database changes to be replicated to other systems.
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