IBM 000-8697 Ready LTAPEDEV, Locate the Next Logical Log, Copy Blobpages

Data Consistency, Recovery, and Migration 4-27
Ready LTAPEDEV
Ready LTAPEDEV
Whenyou request a logical log backup, you are prompted to mount a tape on
the tape device specified asLTAPEDEV in the configuration file. The tbtape
process prompts you to verify that the tape device is ready.
If the tape is new, thetbtape utility process writes a tape header page to the
device. This tape header page contains the following information:
■The tape device block size (LTAPEBLK)
■The size of tape (LTAPESIZE)
■A flag that indicates the tape is for logical log backup
■A timestamp that indicates the date
Locate the Next Logical Log
The tbtape process locates the oldest logical log file that has been used but
not backed up (statusU).
OnLinebacks up all full logical logs. If more than one tape is needed, OnLine
providesyou with labelling information for the full tape and prompts you to
mount a new tape.
If Continuous-Logging is chosen,tbtape begins to back up all currently full
logfiles. The tbtape process then waits for the current log to become full. As
each log file becomes full,tbtape automatically initiates a back up.
Copy Blobpages
Thetbtape process begins by comparing the identification number of the log
fileit is backing up with every entry on every blobspace free-map page. The
tbtape process is looking for blobpages that were allocated during the time
thislogical log file was the current log file. (Refer to page 2-148 for more infor-
mation about the blobspace free-map page and its role in logical log file
backups.)