Mysql replication problem after export/import on already working replication
I would check the export process.

If you use mysqldump, create this script on the Slave and execute it on the Slave:

#
# Dump the Master
# Use the coordinates of the Master at the point the mysqldump starts
#
DUMPFILE=/path/to/dumpfile.sql
MYSQL_USER=masterroot
MYSQL_PASS=masterrootpassword
MYSQL_CONN="-u${MYSQL_USER} -p ${MYSQL_PASS}"
SQL="SELECT GROUP_CONCAT(schema_name) FROM information_schema.schemata"
SQL="${SQL} WHERE schema_name NOT IN ('information_schema','mysql','performance_schema')"
DBLIST=`mysql ${MYSQL_CONN} -ANe"${SQL}" | sed 's/,/ /g'`
echo "STOP SLAVE;" &gt; ${DUMPFILE}
MYSQLDUMP_OPTIONS="--master_data=1"
MYSQLDUMP_OPTIONS="${MYSQLDUMP_OPTIONS} --single-transaction"
MYSQLDUMP_OPTIONS="${MYSQLDUMP_OPTIONS} --routines"
MYSQLDUMP_OPTIONS="${MYSQLDUMP_OPTIONS} --triggers"
MYSQLDUMP_OPTIONS="${MYSQLDUMP_OPTIONS} --add-drop-database"
mysqldump -h ipaddrofmaster ${MYSQL_CONN} ${MYSQLDUMP_OPTIONS} -B ${DBLIST} &gt;&gt; ${DUMPFILE}
echo "START SLAVE;" &gt;&gt; ${DUMPFILE}
#
# Load the Slave
#
MYSQL_USER=slaveroot
MYSQL_PASS=slaverootpassword
MYSQL_CONN="-u${MYSQL_USER} -p ${MYSQL_PASS}"
mysql -h localhost ${MYSQL_CONN} &lt; ${DUMPFILE}


This script will move all user-defined database. It will not import the mysql schema from the Master. This is designed so that the Master can be from an earlier version of MySQL than the Slave and will still import the data. All grants should be left in tact.

You need to make sure of the following:


the Master and Slave are using the same binlog_format (Being Cautious)
the Master and Slave are using two different values for server_id


If Slave_IO_Running is Yes, Slave_SQL_Running is Yes, you are definitely writing on the Master, and the Relay_Log_Space is not moving, then one of the following might be happening


the Slave ran out of diskspace because MySQL will freeze solid with no diskspace
The I/O has silently stopped heartbeating (Derek Downey mentioned this in hist old post Can we capture only Slave_IO_Running in SHOW SLAVE STATUS in MySQL)