mysqldump --single-transaction --user=user_name --password=your_password redmine_database > backup.sql

tar czvf redmine_backup.tar.gz /path/too/redmine/installation

# Database
/usr/bin/mysqldump -u <username> -p<password> <redmine_database> | gzip > /path/to/backup/db/redmine_`date +%y_%m_%d`.gz

# Attachments
rsync -a /path/to/redmine/files /path/to/backup/files