#
# backup mysql database
#
# m = minute (0-59)
# h = hour (0-23)
# dom = day of the month (1-31)
# mon = month (1-12)
# dow = day of the week (0-7)
#
# m h dom mon dow user command
15 3 * * * root /usr/local/bin/mysqlbackup

create directory to hold backups
#mkdir /data/mysqlbackup
/usr/local/bin/mysqlbackup
#!/bin/sh
mysqldump -u root -pmythtv --databases mysql mythconverg > /data/mysqlbackup/mythtv`date +%u`.sql
(this will create 7 backup files 1=Monday, 2=Tuesday.... and overwrite the files every week to save space)

#chmod 755 /usr/local/bin/mysqlbackup 



Optimize database
To regularly optimize the database create a scipt /usr/local/bin/optimize_mythdb.sh 

#!/bin/sh

OPT_MYTHDB='/usr/share/doc/mythtv-backend/contrib/maintenance/optimize_mythdb.pl'
LOG='/var/log/mythtv/optimize_mythdb.log'

echo "Started ${OPT_MYTHDB} on `date`" >> ${LOG}
${OPT_MYTHDB} >> ${LOG}
echo "Finished ${OPT_MYTHDB} on `date`" >> ${LOG}


and a cron job: etc/cron.d/optimize_mythdb 

#
# m   = minute           (0-59)
# h   = hour             (0-23)
# dom = day of the month (1-31)
# mon = month            (1-12)
# dow = day of the week  (0-7)
#
# m h dom mon dow user    command
  0 3  *   *   1  root    /usr/local/bin/optimize_mythdb.sh > /dev/null 2>&1

Full backup
Boot from USB rescue disk (e.g. Ubuntu live)
# sudo su - (become root)
# mkdir /data (create mount point)
# mount /dev/sda1 /data (mount MythTV data disk on /data, this is where we will store the backup of the boot disk sdb1)
# mkdir /data/mythtvbackup
# dd if=/dev/sdb of=/data/mythtvbackup/yyyymmddMythtv16_04MBR.dd bs=512 count=1 (backup master boot record of mythtv disk)
# dd if=/dev/sdb1 of=/data/mythtvbackup/yyyymmddMythtv16_04Root.dd status=progress (backup root file system of mythtv disk)

The dd backups can be a good backup if your disk crashes. If you just need one file, you can also make a file backup
# mkdir /mythtvroot (create mount point)
# mount /dev/sdb1 /mythtvroot
# mkdir /mythtvroot/FilesAndFolders
# tar cf - . | (cd /data/mythtvbackup/FilesAndFolders && tar xBf -)