Dump Mysql stack my web server , it needs improvments

Hi to all of you ,
I have the following configuration:
I have a Linux server running apache and mysql 5.5
At night there is a cron job running (see it below, it's simple as I'm new to bash ) we use it to dump the db and transfer it to a remote server on an Internet repository.

problem:
during the period of the dump/transfer of the Database the web site goes offline ( I have a monitor tool called pingdom ) .

I feel the problem is the mysql service taking all the resources for the dump, how can I improve the script?

Thank you
Carlo
 


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#!/bin/bash
# Path to backup directories
DIRS="/var/www/html/"

# Store backup path
BACKUP="/pippobackup/"

# Backup file name hostname.time.tar.gz
BFILE="files.tar.gz"
MFILE="database.mysql.sq.gz"


# Set MySQL username and password
MYSQLUSER="root"
MYSQLPASSWORD="aaabbbcccddd"

# Remote SSH server setup
SSHSERVER="192.937.965.934" # your remote ssh server
SSHUSER="root"                # username
SSHDUMPDIR="/backup/remote"    # remote ssh server directory to store dumps

# Paths for binary files
TAR="/bin/tar"
PGDUMP="/usr/bin/pg_dump"
MYSQLDUMP="/usr/bin/mysqldump"
GZIP="/bin/gzip"
SCP="/usr/bin/scp"
SSH="/usr/bin/ssh"
LOGGER="/usr/bin/logger"


# make sure backup directory exists
[ ! -d $BACKUP ] && mkdir -p ${BACKUP}

# Log backup start time in /var/log/messages
$LOGGER "$0: *** Backup started @ $(date) ***"

# Backup MySQL
$MYSQLDUMP  -u ${MYSQLUSER} -h localhost -p${MYSQLPASSWORD} --all-databases | $GZIP -9 > ${BACKUP}/${MFILE}

# Dump all local files to failsafe remote UNIX ssh server / home server
$SSH ${SSHUSER}@${SSHSERVER} mkdir -p ${SSHDUMPDIR}
$SCP -r ${BACKUP}/* ${SSHUSER}@${SSHSERVER}:${SSHDUMPDIR}

# Log backup end time in /var/log/messages
$LOGGER "$0: *** Backup Ended @ $(date) ***"