From Online Manual
Please see SMF1.1:Forum Maintenance or SMF2.0:Forum Maintenance depending on the version of SMF you are using.
- Check all files against current versions - Running this task will tell you which of your files need to be upgraded.
- Find and repair any errors - Running this task will search for any possible errors in your database. Usually, these errors are caused by improper conversions, modifications gone wrong, or data corruption. It is a good idea to check this once in a while, just in case.
- Recount all forum totals and statistics - Running this task will recount the number of posts and topics in each board, the number of personal messages each member has, and a few other statistics.
- Empty out unimportant logs - Running this task empties a few of the less important log tables. This is not necessary, unless you really want to save database space.
- Empty file cache - Running this task will empty out the files generated by SMF for caching purposes.
- Optimize all tables to improve performance. - Running this task will get rid of overhead, effectively making the tables smaller in size and your forum faster! Note that it causes SMF to instruct the database to attempt to re-analyze and re-optimize the tables in your database, so it is not a good idea to run this too often, because it can take a long time.
- Backup Database - This area allows you to save a copy of all the posts, settings, members, and other information in your forum to a very large file. For larger forums, this backup may not be able to backup your entire database, in which case you may want to backup your data by other means, such as using phpmyadmin, or some other database backup utility. Frequent backups are recommended, perhaps weekly, for safety and security.
- Convert HTML-entities to UTF-8 characters - Running this task will convert your character set for both your database and data to UTF-8. This should be run with caution, as it is not desirable in all cases. Upon clicking this link you will receive more information on the effects of converting to UTF-8. SMF will attempt to detect your character set for your data, but if you know your data character set is different from the one which is detected, you can change it using the dropdown menu next to Data character set. This option is only available if SMF detects a compatible database version.
- Reattribute User Posts - This function assigns a guest's posts to a specific registered user based on the email address or the username used to post.
- Remove Inactive Members - This function allows the removal of inactive users. It is possible to delete all users who have not logged in for a defined period of time, or who have not activated the account. It is also possible to select to prune only one or more membergroups.
- Remove Old Posts - This allows admins to remove old topics that have not been posted in for the specified number of days. It is possible to narrow down the posts to delete by selecting from removing any type of topic, moved topic notices, or locked topics. The option But don't count stickied topics prevents the removal of topics which have been stickied. Additionally, expanding the All Boards link, and checking boards, will ensure that topics will be removed only from those boards which have been selected. Please note that this is a manual process, so it will not be repeated automatically.
- Move Topics - This allows you to move all the topics in one board to another.