SQL/MP Installation and Management Guide

Performing Recovery Operations
HP NonStop SQL/MP Installation and Management Guide—523353-004
11-13
File Recovery
File Recovery
File recovery is usually the recovery method used if other methods have failed. File
recovery can be used only if you consistently dump audit trails to tape and make online
dumps. File recovery reconstructs an audited file from the initial starting point of the
online dumps and applies all the changes to the file from the history of the audit trails.
The file is recovered to the last consistent point in the database. These guidelines
apply:
•
The file recovery process is invoked by issuing the RECOVER FILES command to
one of the TMF interfaces (such as TMFCOM). The file recovery process prompts
the operator for the online dumps and audit-trail tapes as needed. Audit trails that
still reside on disk are read directly from disk.
•
If you do not specify the FROMARCHIVE option in the RECOVER FILES
command, the file recovery process recovers only the files marked undo-needed. If
you specify the FROM ARCHIVE option of the RECOVER FILES command, file
recovery tries to recover the entire file set, regardless of the setting of the redo-
needed and undo-needed flags.
•
The file recovery process cannot recover any file that did not exist at the time of an
online dump. The file recovery process cannot perform a create function. You must
perform an online dump following any create operation. If you do not perform this
dump, you cannot recover the file because the TMF subsystem looks for a starting
point on the most recent online dump.
•
If your database uses a scheme of audited and nonaudited files, you might not be
able to recover a consistent database, depending on the date and time of the most
recent BACKUP and TMF recovery point of audited files. You must then manually
attempt to put the database into a consistent state.
•
A REDONEEDED or UNDONEEDED flag in the FILEINFO display for a file
indicates that you must use file recovery to recover the file.
•
If your system uses the SMF product to manage disk volumes, TMF file recovery
procedures might differ slightly from those described in these sections. For
example, a file might be recovered to a different disk volume if the volume on
which it originally resided is not available. For more information about how TMF
performs file recovery on volumes managed by SMF, see TMF manuals. For more
information about SMF, see the Storage Management Foundation User’s Guide.