Operating OnLine 3-17
Examine Your Logical Log Configuration
If theLTAPEDEV and TAPEDEV values are the same, you must plan your
logicallog file backups to leave the maximum amount of free space available
beforethe archive begins. If the logical log files fill while the archive is under
way, normal OnLine processing stops. If this happens, your options are
limited. You can either abort the archive to free the tape device and back up
the logical logs or leave normal processing suspended until the archive
completes.
Youmight decide to set LTAPEDEVto /dev/null (and not keep logical log file
backups) under the following conditions:
Ifyour environment does not include a tape device but you want to
use OnLine, set bothLTAPEDEV and TAPEDEV (the archive tape
device) to/dev/null.
If you do not care about data recovery beyond the information that
is available from archives, setLTAPEDEV to /dev/null. If data
recoveryis irrelevant, set both LTAPEDEVand TAPEDEV to /dev/null.
WhenLTAPEDEVis set to /dev/null, OnLine does not wait for a backup before
markingthe logical log files as backed up. Instead, as soon as a logical log file
becomes full, it is immediately marked as backed up (status B).
Whenthe last open transaction in the log is closed, the log file is marked free
(status F). As a result, no logical log data is stored. This means that, in the
eventof failure, you cannot restore work done since the most-recent archive.
LTAPEBLK and LTAPESIZE
Verifythat the current block size and tape size are appropriate for the device
specified. The block size of the logical log tape device is specified as
LTAPEBLK. The tape size is specified asLTAPESIZE.
IfLTAPEDEV is specified as /dev/null, block size and tape size are ignored.
SpecifyLTAPEBLK as the largest block size permitted by your tape device.
SpecifyLTAPESIZE as the maximum amount of data you can write to this
tape.