Offline AMPs
The Teradata Database configuration determines how to archive when AMPs are offline. If a table has fallback protection or dual after-image journaling, Teradata ARC makes a complete copy of the data rows, even if an AMP (per cluster) is offline during the archive. For a cluster archive, only AMPs within specified clusters are considered.
All Teradata Database dictionary rows are defined with fallback. Therefore, Teradata ARC always performs a complete archive of the necessary dictionary entries, even if AMPs are offline. This is also true when database DBC is archived.
Consider a situation where:
In this situation, a specific AMP archive for the offline processors after the AMPs are back online is required.
Single after-images (remote or local) are maintained on single AMPs, therefore after-images for offline AMPs are not included in the archive. If one of these archives is restored with a rollforward operation, data from some of the online AMPs is not rolled forward.
Example 1
This example archives all databases when one AMP is offline with Teradata Database. In this case, the offline AMP is not out of service because of a disk failure.
LOGON DBC,DBC;
ARCHIVE DATA TABLES (DBC) ALL,
RELEASE LOCK,
INDEXES,
FILE=ARCHIVE;
LOGOFF;
When the archive operation is complete, check the print file to verify that the offline AMP did not come back online during the archive. If the offline AMP came back online during the archive, the print file reports the following with Teradata Database, where n is the number of the AMP:
AMP n BACK ON-LINE
When the offline AMP returns to online operation, run another archive procedure to archive rows from the offline AMP, even if the AMP came back online during the archive.
Example 2
This example archives all nonfallback data from an AMP that was offline during a previous Teradata Database archive operation.
LOGON DBC,DBC;
ARCHIVE NO FALLBACK TABLES (DBC) ALL,
AMP=3,
EXCLUDE (DBC),
RELEASE LOCK,
FILE=ARCHIVE;
LOGOFF;