What does this event mean?
In both events, log file switch (archiving needed) and
log file switch (checkpoint incomplete), the LGWR is unable
to switch into the next online redo log, and all the commit requests wait
for this event.
What actions can be taken?
For the log file switch (archiving needed) event, examine why the archiver
is unable to archive the logs in a timely fashion. It could be due to the
following:
- Archive destination is running out of free space.
- Archiver is not able to read redo logs fast enough (contention with
the LGWR).
- Archiver is not able to write fast enough (contention on the archive
destination, or not enough ARCH processes).
Depending on the nature of bottleneck, you might need to redistribute I/O
or add more space to the archive destination to alleviate the problem. For
the log file switch (checkpoint incomplete) event:
- Check if DBWR is slow, possibly due to an overloaded or slow I/O
system. Check the DBWR write times, check the I/O system, and
distribute I/O if necessary.
- Check if there are too few, or too small redo logs. If you have a few
and/or small redo logs (for example two x 100k logs), and your system
produces enough redo to cycle through all of the logs before DBWR has
been able to complete the checkpoint, then increase the size and/or
number of redo logs.
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