For pre-Oracle Database 10g systems, the wait event will be latch free, with the associated latch being redo copy. For later systems, the wait event is simply latch free: redo copy. Regardless of your Oracle release, a simple and very effective solution is to increase the instance parameter _log_simultaneous_copies, which will increase the number of redo copy latches. This is an elegant solution that is very likely to eliminate redo copy latch contention without requiring any changes to either the operating system or to the application.

As discussed in the previous section, in pre-Oracle9i systems, the redo copy latch can also be used to allocate space in the redo log buffer. So, one Oracle-focused option is to increase the _log_small_entry_max_size instance parameter. Because this hidden instance parameter affects both the redo allocation and redo copy latches, a more direct solution is to simply add more redo copy latches.

The title of this section is a little misleading because the contention is centered on commit times taking an unacceptably long period. When this occurs, the top wait event will be log file sync. If users occasionally commit, they may not feel like performance is slow (the good news). However, users who frequently commit, especially when a rapid committing piece of code is involved, will certainly feel the effect and have a considerable amount of their wait time associated with the log file sync wait event.