16.10 - Supported State Transitions - Teradata Unity

Teradata Unity User Guide

Product
Teradata Unity
Release Number
16.10
Published
January 2018
Language
English (United States)
Last Update
2018-03-29
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This table describes Unity system and table states and shows supported transition states.
State Current State Description Supported State Transitions
Active Table is available for Read/Write operations. Data synchronization is enabled on Active systems.
  • OOS (Out of Service): This allows you to halt table synchronization.
  • Read-only: This allows you to freeze the table. A table may also automatically be placed in Read-only if a session encounters an error and the SetReadOnlyOnWriteFailure parameter is set to true.
Standby Database table is up-to-date and available for failover Read/Write operations.
  • Active
Interrupted An error occurred on a table for one system. This error was not duplicated for the same table on other systems. This error is potentially recoverable. Until the system recovers from the interruption, tables in this state are unavailable. For example, when a session cannot be opened on a Teradata Database system due to insufficient Teradata Database system resources, the state changes to Interrupted.
  • Restore:

    Table normally recovers automatically. Investigate the problem that caused the interruption before attempting to restore to an Active state. If the problem is not resolved, the interruption may reoccur.

    After the problem is resolved, to force recovery, place the table in the Restore state. This synchronizes data and sets the table state to the Active state.

Read-only In a Read-Only state, only Read access is allowed to the Teradata Database system or table.
  • Restore: To change the table to Read/Write, use the Restore state. This synchronizes data and sets the table state to the Active state.
Restore Table is in active recovery operation. Unity applies any missed Write operations from the Recovery Log.
  • Active: After restore completes, verify the table was successfully recovered and placed in the Active state.
OOS No Read or Write requests are being sent to this table in the Out of Service state.
  • Restore: To recover from this state, place the table in the Restore state. This synchronizes data and sets the table state to the Active state.
Unrecoverable System or table is unavailable. Because Unity does not recognize the state of the data, it does not automatically recover a table in the Unrecoverable state.
  • Active:
For database tables: Tables in the Unrecoverable state must be synchronized manually. You cannot restore a table if it is unrecoverable on one system and active on another. You must mark the active table as unrecoverable and activate the table across all systems.

For Teradata systems: During configuration, a Teradata system are first placed in an Unrecoverable state. If all system are Unrecoverable, you must manually synchronize the data across all your Teradata systems. You can activate all systems in the Components pane.