Compaq Reliable Transaction Router manual Shadow, Standby, Transaction controller

shadow

The state of the server process that services a copy of the data store or primary database. In the context of RTR, the shadow method is transactional shadowing, not disk shadowing. Its counterpart is primary.

SMP

Symmetric MultiProcessing.

standby

The state of the partition that can take over if the process for which it is on standby is unavailable. It is held in reserve, ready for use.

TPS

Transactions per second.

transaction

An operation performed on a database, typically causing an update to the database. Analogous in many cases to a business transaction such as executing a stock trade or purchasing an item in a store. A business transaction may consist of one or more than one RTR transaction. A transaction is classified as original, replay, or recovery, depending on how it arrives at the backend:

Original—Transaction arrived on the first attempt from the client.

Replay—Transaction arrived after some failure as the result of a re-send from the client (that is, from the client transaction-replay buffers in the RTRACP). Recovery—Transaction arrived as the result of a backend- to-backend recovery operation (recovery from the journal).

transaction controller

A transaction controller processes transactions. A transaction controller may have 0 or 1 transactions active at any moment in time. It is through the transaction controller that messages and events are sent and received.

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