One strategy is to increase the redo log buffer size, enabling it to absorb redo activity bursts, thereby reducing the likelihood of log buffer space wait events. Then decrease the _log_io_size parameter to ensure the log writer background process is performing more frequent, smaller redo log buffer flushes to keep performance smooth and consistent. However, be aware that if the _log_io_size parameter is set too small, the log writer would be making frequent and relatively small and inefficient writes, causing other problems. Once again, the performance analyst must find that elusive performance balance.

As Figure 8-6 clearly shows, even an inactive log writer background process will wake up every 3 seconds, even if it's just to flush the general redo log buffer. However, in Oracle9i Release 2, which introduced redo strands, experiments demonstrate the entire redo log buffer is not flushed every 3 seconds; only the general redo log buffer is flushed.

The output shown in Figure 8-6, which contains no write statements over a 9-second interval, occurred while updates were being issued about once each second! This demonstrates the log writer background process does not flush the enter redo log buffer every 3 seconds. Thankfully, as soon as a commit was issued, the log writer immediately issued a write call to the operating system.