[Linux-cluster] MySQL Failover / Failback

[Robert Gil]

I figured this problem out. In order to do a vip, both the host ip and
the vip need to be in the same subnet.
 
Robert Gil
Linux Systems Administrator
American Home Mortgage
Phone: 631-622-8410
Cell: 631-827-5775
Fax: 516-495-5861
 

________________________________

From: linux-cluster-bounces at redhat.com
[mailto:linux-cluster-bounces at redhat.com] On Behalf Of Robert Gil
Sent: Friday, June 01, 2007 1:45 PM
To: linux clustering
Subject: RE: [Linux-cluster] MySQL Failover / Failback


Sorry, forgot the error message in here.
 


From: linux-cluster-bounces at redhat.com
[mailto:linux-cluster-bounces at redhat.com] On Behalf Of Robert Gil
Sent: Friday, June 01, 2007 1:43 PM
To: linux clustering
Subject: RE: [Linux-cluster] MySQL Failover / Failback


 


From: linux-cluster-bounces at redhat.com
[mailto:linux-cluster-bounces at redhat.com] On Behalf Of Jeff Stoner
Sent: Friday, June 01, 2007 1:21 PM
To: linux clustering
Subject: RE: [Linux-cluster] MySQL Failover / Failback


Sounds like you've got several things happening all at once. If you are
not using MySQL Cluster, then you will probably have an active/passive
setup, in which MySQL will be running on only one node. If you are using
MySQL Cluster, why are you using Redhat Cluster?
 
Yes, it is using mysql replication NOT mysql cluster. It is active /
passive. One node is rw (master) the other is ro (slave).
 
Replication? Are you referring to MySQL Replication? What is replicating
where? Are the slaves a part of the Redhat Cluster? If you simply mean
will replication "break" if MySQL fails over then no. Replication on the
slave will retry connecting to the master (according to the connection
retry settings in MySQL.) Also, you must use the Redhat
Cluster-controlled IP when establishing replication and not the IP of
any particular node (for obvious reasons.)
 
For my MySQL databases built on Redhat Cluster, I specify my service as
follows:
 
<service autostart="1" domain="mysql-fail-domain" name="mysql5-service">
   <ip ref="10.2.2.2"/>
   <fs ref="mysqlfs"/>
   <script ref="mysqld"/>
</service>

The filesystem resource is a slice of SAN accessible by all nodes in the
cluster. The script is a (modified) /etc/init.d/mysqld script.
 
 
What does your resource section look like for the ip address? I keep
getting the following errors (posted in another message)
 
Jun  1 13:29:10 melpsjssdbs01 clurgmgrd[5346]: <notice> Starting
disabled service mastervip
Jun  1 13:29:10 melpsjssdbs01 clurgmgrd[5346]: <notice> start on
ip:192.168.2.100 returned 1 (generic error)
Jun  1 13:29:10 melpsjssdbs01 clurgmgrd[5346]: <warning> #68: Failed to
start mastervip; return value: 1
Jun  1 13:29:10 melpsjssdbs01 clurgmgrd[5346]: <notice> Stopping service
mastervip
Jun  1 13:29:10 melpsjssdbs01 clurgmgrd[5346]: <notice> Service
mastervip is recovering
Jun  1 13:29:10 melpsjssdbs01 clurgmgrd[5346]: <warning> #71: Relocating
failed service mastervip
Jun  1 13:29:11 melpsjssdbs01 clurgmgrd[5346]: <warning> #70: Attempting
to restart service mastervip locally.
Jun  1 13:29:11 melpsjssdbs01 clurgmgrd[5346]: <notice> Recovering
failed service mastervip
Jun  1 13:29:11 melpsjssdbs01 clurgmgrd[5346]: <notice> start on
ip:192.168.2.100 returned 1 (generic error)
Jun  1 13:29:11 melpsjssdbs01 clurgmgrd[5346]: <warning> #68: Failed to
start mastervip; return value: 1
Jun  1 13:29:11 melpsjssdbs01 clurgmgrd[5346]: <notice> Stopping service
mastervip
Jun  1 13:29:11 melpsjssdbs01 clurgmgrd[5346]: <notice> Service
mastervip is stopped


--Jeff

Service Engineer
OpSource Inc.

"The Message of the Day is /etc/motd"


 



________________________________


	I am curious if anyone knows the best practices for this?
Several use cases include
	 
	Note: We are choosing to use a vip for the two nodes to make the
failover change transparent to the application side.
	 
	1) Node 1 (master) dies
	        -How do we enable "sticky" failover so that it does not
then fail back to Node 1
	        -Is Node 2 active all the time or is the service
completely shut off? And if its off, how would replication happen?
	        -How do failover domains work in this case?
	2) Node 2 (Master) Node 1 recovered
	        -How does replication continue again?
	        -How does the master slave relationship change? Is this
automated, or does it require manual intervention? Should we be using
DRDB?
	3) Node 1 (master) Node 2 (slave) - network connectivity dies on
node 1
	        -There is an IP resource available, but how does this
monitor and handle failover?
	        -How can I move the vip in the event of a failure? Do I
need to manually script this?
	 
	With the vip failover, do I attach the vip resource to the mysql
resource in the failover domain for those two nodes? What happens if I
do this?
	 

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