I have a website running on a MySQL database backend which is backed up daily by the following command:
mysqldump -h server.com -uuser -ppass database > /home/directory/backup`date +"%Y%m%d"`.sql
I've noticed that as the database has got larger and the backup takes longer (maybe a few minutes) the site does not function correctly during the backup process.
Pages which require database loaded during the backup hang during the backup and fail to load until the backup is complete. Often they don't seem to timeout, until after the backup is complete with a MySql timeout 30 seconds error - even though more than 30 seconds has passed.
I guess the mysqldump command is locking access to some part of the database and preventing client connections from the webserver, but can't find any more information about this.
I'm running mysql 5 on the server and the tables are in ISAM format.