Ever since I've been running phpBB when it comes to backing up the database I always use the ACP option to back up all tables as a gZip file, but I also go into phpMyAdmin and dump out the tables used for the forum.
Is one method better than the other, should I just use one?
The ACP backup will backup everything needed, however it's limited by the resources provided by your host (e.g. some tables might be too large to do a full backup)
With phpMyAdmin (or similar) it's possible to take deeply fractioned backups of a table.
An ACP-made backup can be restored by phpBB itself, a phpMyAdmin not (without some editing).
When starting a board, database size en server resources shouldn't be an issue so the ACP backup is the easiest (and safe) option.. Even with larger databases the ACP option is usually sufficient (search tables don't need backing up, as they can be repopulated anytime, and other large tables can be backuped separately).
Conclusion: stick to the ACP backup unless it fails for one reason or another.
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