TMF Operations and Recovery Guide (G06.24+)

Recovery Methods
HP NonStop TMF Operations and Recovery Guide—522417-002
7-7
File Recovery
File Recovery
The file recovery process reconstructs audited files when the copy on disk is not
usable. A file could become unusable for one or more of the following reasons:
•
A disk media failure occurs.
•
The volume recovery process recovers a data volume but is unable to recover one
or more of the audited files that reside there.
•
An audited file is mistakenly purged.
•
An application program incorrectly changes the database.
•
Records or rows are mistakenly inserted or deleted by an end user through the
SQL conversational interface or an Enscribe database maintenance utility.
While backout and volume recovery require the audited files on disk to be readable, file
recovery does not. The file recovery process can use audit-trail files on disk, online
dumps, and audit dumps to recover a file: the data it uses depends on the options you
specify in the RECOVER FILES command.
RECOVER FILES Command With FROMARCHIVE Option
When you issue a RECOVER FILES command with the FROMARCHIVE option, the
file recovery process recovers all files required, regardless of the flags set in the file
labels. Specifically, file recovery performs the following steps:
1. Sends requests to the TMFDR (TMF dump/restore) process to restore the
specified files from online dumps.
2. Reads online dump files from the most recent readable copy and replaces the
crashed files on disk.
3. Reads the necessary audit-trail files either from the active volume or from audit
dumps. Audit dumps are needed if the audit records needed to recover files are no
longer in the active-audit trail. If audit dumps are required, they are copied to the
audit trail’s restore-audit volume.
4. Reapplies all the changes recorded in the audit-trail files after the online dump was
made. File recovery begins with the audit-trail file that was active when the online
dump was performed, and then proceeds through subsequent audit-trail files
sequentially, up to the current one. During this step, the file recovery process
generates EMS Message 401:
Phase 1 of recovery completed at
atseqno atseqno RBA rba.
Note. To recover a file that sent data to an auxiliary audit trail, the file recovery process
needs audit records from the auxiliary audit trail as well as records from the master audit
trail. In most cases, this requires you to mount audit dump tapes from both audit trails.