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Operating OnLine 3-43
Archive Administration
This process continues with each log file on Tape A. When the restore process
encounters the partial log at the end of Tape A, it reads what records it can.
Because OnLine has not reached the end of the log file, it prompts the
operator for the next tape.
The operator mounts Tape B. OnLine reads the logical log header indicating
that this is the beginning of the same log file that has been partially read. At
this point, the restore procedure ignores the partial log information read at
the end of Tape A and begins to read the complete log as it exists on Tape B.
If, in response to the prompt for the next tape, the operator indicates that no
more tapes exist, the restore process begins to roll forward whatever records
it can from the partial log on Tape A. All records that are part of incomplete
transactions are rolled back.
Archive Administration
For an explanation of what happens during an archive and how OnLine
determines which disk pages to copy to tape, refer to page 4-30.
For information about the role of an archive in an OnLine data restore, refer
to page 4-45.
Archive Types
An archive is a copy of OnLine data at a specific time, stored on one or more
volumes of tape. OnLine supports three-tiered incremental archives:
■ Level-0, the base-line archive
■ Level-1, all changes since the last level-0 archive
■ Level-2, all changes since the last level-1 or level-2 archive
You can create archives (any level) when OnLine is in online mode or
quiescent mode. You can also create an archive remotely: that is, when the
tape device is managed by a different machine. Each of these archives is
explained in the following paragraphs.