If your Oracle redo log file is undersized, you will run into the wait event: log file switch (checkpoint incomplete).

Another way to judge redo logfile sizing is by examining Checkpoint Activity in the Oracle AWR report. The distribution of checkpoint writes reveals whether Oracle is checkpointing smoothly or struggling due to undersized logs.

Adeaquately Sized Logfiles

Below is the Checkpoint Activity section from a AWR report where the logfiles were adequately sized:

Here, nearly all writes are Autotune Ckpt Writes, which is a healthy pattern. Oracle’s MTTR (Mean Time To Recover) tuning mechanism is in control, spreading out writes evenly to meet the recovery target. This avoids sudden spikes in redo writing and keeps checkpoints proactive rather than reactive.

Inadeaquately Sized Logfiles

Now compare that with an Oracle database where the logfiles were too small:

In this case, the majority of writes are:

• Thread Ckpt Writes — triggered by log file swithes.
• Log Size Writes— occur when Oracle needs to reuse a redo log file, but the checkpoint position hasn’t yet advanced past it. In this situation, sessions generating redo are forced to wait on “log file switch (checkpoint incomplete)” event until the log switch is done.

This pattern indicates that Oracle is checkpointing reactively due to undersized redo log files, instead of proactively through MTTR tuning.

When redo log files size is unadequate, the solution is to either increase the size of redo logfiles, add more log groups to spread out switches, or apply a combination of both.