16.10 - The Reconfiguration Process - Teradata Database

Teradata Database Support Utilities

prodname
Teradata Database
vrm_release
16.10
created_date
June 2017
category
Configuration
featnum
B035-1180-161K

This section summarizes the reconfiguration process. Individual Reconfiguration commands are described in Reconfiguration Utility Commands.

As Reconfiguration runs, it performs these functions:

  • Checks the Teradata Database system status to ensure that reconfiguration is possible.

    Disk storage capacity is checked to ensure that the Teradata Database system has sufficient storage to accommodate the redistributed data in the event of a delete AMP reconfiguration. Reconfiguration terminates if the Teradata Database system does not have sufficient storage capacity.

    After Teradata Database system status is verified, new hash bucket arrays are calculated based on current and new configuration maps.

  • Redistributes primary and fallback data for tables that are processed by the Reconfiguration utility. Unique secondary index subtables, if any, are redistributed also. For PA and NoPI tables, no rows are redistributed when adding AMPs.
  • Deletes rows that were redistributed from AMPs on which they resided before the redistribution. Nonunique secondary indexes, if any, are rebuilt.
  • Updates space accounting information, hash bucket arrays, and configuration maps.

You start the Reconfiguration utility from Database Window or from a comparable interface to the Teradata Database console subsystem, such as the cnsterm Linux command-line tool. For general information on starting the utilities, see Starting the Utilities.

After the utility is started, start the actual reconfiguration by typing reconfig at the Reconfiguration utility command prompt. For more information on the RECONFIG command, see RECONFIG.

The WITH PAUSE option causes reconfiguration to pause before entering the auto-restart phase, the point beyond which reconfiguration will automatically restart if Teradata Database restarts. The point at which the auto-restart phase begins depends on the purpose of the reconfiguration:

  • If reconfiguration is for adding, deleting, or moving AMPs, for cluster reassignments, the auto-restart phase begins at the beginning of table redistribution.
  • For all other reconfiguration purposes, the auto-restart phase begins when that new primary hash map is saved.

The reconfiguration proceeds sequentially in this order:

  1. During initialization, the Reconfiguration utility verifies that table headers for every table exist on the appropriate AMPs, according to the map used by each table.
    If a table header is missing, the table ID and the corresponding vproc ID from which the header is missing are displayed in the Database Window, and at the end of the verification, reconfig displays the following message:
    DBS Table Header verification failed, the missing header is available on the Database Window. Repair all missing table headers before reattempting Reconfiguration.
       ***** Depress the ENTER key to reset DBS.
    At this point, you should switch to the Database Window to obtain a list of missing table headers before resetting the Teradata Database system.
    If this error condition occurs, contact the Teradata Support Center for procedures to fix the missing headers.
  2. Before entering the hash map calculation phase, Reconfiguration checks all AMPs for active user sessions. If any users are logged on, Reconfiguration issues an error message and halts.
  3. Reconfig calculates the hash map.
  4. If you used the WITH PAUSE option to the RECONFIG command, Reconfiguration prompts:
    Reconfiguration pauses before the auto-restart phase.
       Do You Want to Abort? Type Y(es) or N(o).

    This is the last opportunity to stop the reconfiguration.

  5. The Table Redistribution phase of Reconfiguration begins changes to data in the current configuration.

    Reconfiguration redistributes tables (including stored procedures, user-defined functions (UDFs), user-defined methods (UDMs), non-value-ordered join indexes, and non-value-ordered hash indexes). Tables are processed in the order specified in DBC.ReconfigRedistOrderV.

    In the table redistribution phase, Reconfiguration verifies that the table to be redistributed exists on all online AMPs before table redistribution is started. This integrity check identifies those database tables that are corrupted between initialization and this phase.

    If a database table is missing from one or more of the online AMPs, the application window shows this message:

    Table DBName.  TBLName
       *** is missing from some of the online AMPs
       *** This table is skipped.

    The Table Redistribution phase is also the auto-restart phase of reconfiguration, beyond which the reconfiguration process will be restarted automatically if the system restarts. The auto-restart phase is the phase beyond which the reconfiguration must continue to completion and cannot be aborted.

  6. Reconfiguration deletes moved rows from tables and rebuilds NUSIs. Tables are processed in the order specified in DBC.ReconfigDeleteOrderV, or in table ID order if no other order has been specified.
  7. Reconfiguration saves the following:
    • New primary hash map
    • New fallback hash map
    • Current primary hash map
    • Current fallback hash map
    • Current configuration map
    • New configuration map
    • Backup IDs
    • New rows in the DBC.Maps tables for the new MAP.
  8. Reconfiguration saves the bitmap hash table.
  9. Reconfiguration updates the following:
    • Disk space
    • Vproc configuration
  10. Reconfiguration displays this message:

    Restart DBS due to completion of Reconfiguration.
       System is about to reset.
    IF... THEN...
    a Teradata Database system restart occurs when Reconfiguration is in the middle of the Hash Map calculation phase the following message appears:
    Hash Map Calculation Phase Begins.
    { Reconfig Phase one -- rcophas1 }
    Hash Map Calculation Phase Ends.
    a restart occurs after the first message and before the second one Reconfiguration will not start automatically during Teradata Database system start up.
    you are adding new AMPs before Reconfiguration a 6140 error message displays if you start Reconfiguration manually after the Teradata Database system comes up.
    6140: RECONFIG aborted due to improper disk initialization procedure.

    In this case, do the following:

    1. Use the ctl utility to change the Start DBS setting on the Debug screen to Off. See the “Control GDO Editor (ctl)” chapter in Utilitiesfor more information.
    2. Restart Teradata Database.
    3. Use the Vproc Manager utility INITVDISK command to initialize the file system on the newly added AMPs. For more information, see the “Vproc Manager (vprocmanager)” chapter in Utilities.
    4. Use the ctl utility to set Start DBS back to On.
    5. Restart Teradata Database.
    6. Start the Reconfiguration utility from Database Window.