Tag Archives: Redhat

MySQL: Migrating Slave to New Master

Consider the following scenario:
Master’s IP address has been changed and the slave needs to be reconfigured for the New IP address.

How do we go about doing it ? Two ways.
One of them a bit hackish but the most
simple:

– Shut down slave MySQL server.
– Find master.info file, store current one in the backup and edit it
replacing the host name with new host name.
– Start slave MySQL server.

Second one is more complex but using only SQL commands:

– Run SLAVE STOP to stop slave thread;
– Run SHOW SLAVE STATUS and record the position in the master binary log
slave is currently located
– use CHANGE MASTER TO to point slave to the same position on the
different hostname
– Use SLAVE START to start slave back again.

We cannot change the IP that easily. We need to do things so complex since MySQL assumes we are
replicating from new slave if you’re changing host name and resets all
other parameters.

Configuring MRTG and NET-SNMP for monitoring Linux System Parameters

Configuration:
MRTG ver. 2.97
Net-SNMP ver. 4.2.6
OS : RedHat Linux 7.3

This doc should help you with configuring a RedHat Linux box for monitoring system parameters (local/remote), using Net-SNMP and MRTG.

About MRTG and Net-SNMP

MRTG (Multi-Router Traffic Grapher)
The Multi Router Traffic Grapher (MRTG) is a tool to monitor the traffic load on network-links. MRTG generates HTML pages containing graphical images which provide a LIVE visual representation of this traffic.
Check http://www.ee.ethz.ch/stats/mrtg/ for an example.
MRTG is based on Perl and C and works under UNIX and Windows NT.
MRTG is being successfully used on many sites around the net

Net-SNMP

Net-SNMP is a collection of various tools relating to the Simple Network Management Protocol including:

* An extensible agent
* An SNMP library
* tools to request or set information from SNMP agents
* tools to generate and handle SNMP traps
* a version of the unix ‘netstat’ command using SNMP
* a graphical Perl/Tk/SNMP based mib browser

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