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From:Johan De Meersman Date:February 18 2014 1:24pm
Subject:Re: Mysql replication setup
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Péter,

If there's sufficient storage on what is to be the master, you might find it easier to use
rsync to make a copy of the running instance's datafiles, then "flush tables with read
lock" and /while that mysql session remains open/ update the copy with a second rsync run
and take the master position. After that, unlock the tables again.

The second rsync run will take considerably less time because it needs only copy the
changed blocks. You can also flush the tables before the first copy (but without the
lock) to ensure a minimum of changes needs to be copied by the second run. Doing the
procedure during a low-traffic period is also helpful, if you have those.

Then simply stick the files under the (shut down, same version) slave instance, and set up
the slave to start from where the master was during the locked rsync.

You could, of course, also rsync straight to the slave, but rsync is considerably faster
locally.

Hope that's useful to you,
Johan

----- Original Message -----
> From: "Balogh Péter" <balogh.peter@stripped>
> To: replication@stripped
> Sent: Monday, 17 February, 2014 6:36:45 PM
> Subject: Mysql replication setup
> 
> Hi,
> 
> I'm building a mysql replication solution to one of our clients, and I
> would like to minimize the downtime during the setup
> We've dealt with replication before, but in this case I would like to
> avoid doing a full locked dump of the db if possible, since the database
> is quite large
> My idea is to start the slave sync with one table, and add all of the
> databases / tables one by one.
> This way, the only down time would be while 1 table gets dumped
> 
> In theory, it should work, does anybody has any experience with a
> solution like this?
> 
> I've put together a script to add a table to a running replication:
> 
> I assume, that the replication is already working for one table, and the
> databases are created ahead
> 
> I've removed the safety checks to make it shorter
> 
> #!/bin/bash
> echo "Step 1. stop slave @ Server2"
> echo STOP SLAVE SQL_THREAD | mysql
> 
> echo "Step 2. export table with locks in place with --master-data option
> @ Server1 and move dump to Server2"
> ssh -i sshkey user@Server1 mysqldump --lock-tables --single-transaction
> --flush-logs --hex-blob --master-data=2 $1 $2>/opt/$1.$2.sql
> 
> binlogFile=`head -n 25 /opt/$1.$2.sql | grep "CHANGE MASTER" | cut -d
> "'" -f 2-2`
> binlogLine=`head -n 25 /opt/$1.$2.sql | grep "CHANGE MASTER" | cut -d
> "=" -f 3- | cut -d ";" -f -1`
> head -n 25 /opt/$1.$2.sql | grep "CHANGE MASTER"
> echo "Parsed file:"$binlogFile" and line:"$binlogLine"."
> 
> echo "Step 3a. run slave until slave sync point @ S2"
> echo START SLAVE SQL_THREAD UNTIL MASTER_LOG_FILE = \'$binlogFile\',
> MASTER_LOG_POS = $binlogLine | mysql
> 
> echo "Step 3b. load table dump"
> mysql $1 < /opt/$1.$2.sql
> 
> echo "Step 3c. add Table1 to my.cnf"
> echo replicate-do-table=$1.$2 >> /etc/mysql/my.cnf
> 
> echo "Step 4. wait until slave finished"
> while [ `echo SHOW SLAVE STATUS \\\\G | mysql | grep "Slave_SQL_Running:
> No" | wc -l` -ne 1 ];do
>          echo "."
>          sleep 1
> done
> 
> echo "Step 5. restart mysql"
> /etc/init.d/mysql restart
> 
> Thank you for your help,
> Best regards,
> Peter Balogh
> 
> --
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> 
> 

-- 
Unhappiness is discouraged and will be corrected with kitten pictures.
Thread
Mysql replication setupBalogh Péter17 Feb 2014
  • Re: Mysql replication setupshawn l.green17 Feb 2014
    • Re: Mysql replication setupJohan De Meersman18 Feb 2014
      • Re: Mysql replication setupshawn l.green19 Feb 2014
        • Re: Mysql replication setupJohan De Meersman19 Feb 2014
          • Re: Mysql replication setupshawn l.green19 Feb 2014
            • Re: Mysql replication setupJohan De Meersman19 Feb 2014
  • Re: Mysql replication setupJohan De Meersman18 Feb 2014
Re: Mysql replication setupJohan De Meersman19 Feb 2014
Re: Mysql replication setupBalogh Péter23 Feb 2014