15.00 - The Reconfiguration Process - Teradata Database

Teradata Database Support Utilities

prodname
Teradata Database
vrm_release
15.00
category
Configuration
featnum
B035-1180-015K

The Reconfiguration Process

This section summarizes the reconfiguration process. Individual Reconfiguration commands are described in “Reconfiguration Utility Commands” on page 255.

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. Unique secondary index subtables, if any, are redistributed also.
  • 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.
  • Reconfiguration functions are completed sequentially in this order:

    1 Before starting Reconfiguration, see “Before Starting Reconfiguration” on page 247.

    2 Start the Reconfiguration utility from Database Window. For general information on starting the utilities, see Appendix B: “Starting the Utilities.”

    3 Start the reconfiguration process by typing RECONFIG at the Reconfiguration utility command prompt. For more information on the RECONFIG command, see “RECONFIG” on page 258.

    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, or for hash bucket size changes, 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.
  • 4 During the initialization of reconfiguration, the existence of all Teradata Database system table headers on all AMPs is verified.

    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.

    At the end of the verification, the following message appears in the application window:

    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.

    Note: If this error condition occurs, contact the Teradata Support Center for procedures to fix the missing headers.

    5 Before entering the hash map calculation phase, Reconfiguration checks all AMPs for active user sessions. If any users are logged on, Reconfiguration asks whether the reconfiguration should continue online, allowing logons to remain enabled. If you respond no, Reconfiguration issues an error message and halts.

    6 Reconfig calculates hash map.

    7 If you requested Reconfiguration to pause in step 3, Reconfiguration prompts:

    Reconfiguration pauses before the auto-restart phase. 
       Do You Want to Abort? Type Y(es) or N(o).
       

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

    The Table Redistribution phase of Reconfiguration begins changes to data in the current configuration. This is the auto-restart phase of reconfiguration, beyond which the process must be run to completion. If the reconfiguration was run online, the ABORT command can be used to stop the reconfiguration and discard all work that has been performed.

    If the reconfiguration was run online to this phase, Reconfiguration now prompts to disable logons and online archiving. When the system is quiescent, reconfiguration continues offline.

    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.

    9 Reconfiguration deletes moved rows from tables and rebuilds NUSIs. (For online reconfiguration, this step is skipped.) Tables are processed in the order specified in DBC.ReconfigDeleteOrderV, or in table ID order if no other order has been specified.

    10 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
  • 11 Reconfiguration deletes new hash maps.

    12 Reconfiguration saves bitmap hash table.

    13 Reconfiguration updates the following:

  • Disk space
  • Vproc configuration
  • 14 If reconfiguration was started online, Reconfiguration now deletes moved rows from tables and rebuilds NUSIs.

    Deletion proceeds offline until all tables are processed.

    When all tables have been processed offline, the database returns online and logons are enabled.

    If reconfiguration did not include an online deletion phase, the system needs to be manually restarted, and 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 Utilities Volume 1 for more information on these utilities.

    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 on the Vproc Manager utility, see Utilities: Volume 1 (A-K).

    4 Use the ctl utility to set Start DBS back to On.

    5 Restart Teradata Database.

    6 Start the Reconfiguration utility from Database Window.

    15 You must drop and rebuild value-ordered join indexes and value-ordered hash indexes before they can be used again after the offline portion of Reconfiguration.