Is MySql locking table during backup and how to avoid? I have a scheduled backup that runs daily in MySQL and I have noticed that during the backup a lot of queries that query a frequently used table seem to take forever to complete. This causes the website to lag like crazy during the backup and once the backup completes, specifically for the frequently used table, the site runs fast again. 

Does MySQL lock table(s) during the backup and if so is there anyway to avoid this?

How do other big systems handle backups without disrupting / slowing their applications?

Thanks
Have you checked Run MySQLDump without Locking Tables question?

Everything boils down to the way you're doing data backups.