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We're using haproxy in front of a 3 node galera cluster, and we see the lost connection stuff pretty often, but that's normal behaviour, MySQL will tear down idle connections, SQLA handles reconnecting fine.

As for deadlocks, if you are distributing writes across your nodes, I'd expect that, we solved it by using haproxy in a primary/backup mode, all traffic flows to one node by default, and fails over to one of the other nodes in the event of a failure, this means that writes are concentrated in a single node & the deadlock & roll back doesn't bite you.

Also - I think you need to be running 3 galera nodes to be safe, as if a partition occurs, you can't cleanly reconnect a node as you can't achieve quorum. (I am not a DBA...)

We're not running Neutron, so I can't comment on that, sorry.

Simon.

On 18 September 2014 at 17:35:18, Sławek Kapłoński (slawek at kaplonski.pl) wrote:

Hello,  

Is anyone here using openstack with mysql galera and haproxy? Have You got any  
problems with that?  
I was today installed such ha infra for database (two mysql servers in galera  
cluster and haproxy on controller and neutron node, this haproxy is connecting  
to one of galera servers with round robin algorithm). Generally all is working  
fine but I have few problems:  
1. I have a lot of messages like:  
WARNING neutron.openstack.common.db.sqlalchemy.session [-] Got mysql server  
has gone away: (2006, 'MySQL server has gone away')  
2. I have (most on neutron) many errors like:  
OperationalError: (OperationalError) (2013, 'Lost connection to MySQL server  
during query') 'UPDATE ml2_port_bindings SET vif_type=%s, driver=%s,  
segment=%s WHERE ml2_port_bindings.port_id =  
3. Also errors:  
StaleDataError: UPDATE statement on table 'ports' expected to update 1 row(s);  
0 were matched.  
4. and errors:  
DBDeadlock: (OperationalError) (1213, 'Deadlock found when trying to get lock;  
try restarting transaction') 'UPDATE ipavailabilityranges SET first_ip=%s WHERE  
ipavailabilityranges.allocation_pool_id =  

Sql queries in examples are "accidental" and same problem is with other  
queries also (like deleting ports).  
Strange think is that those problems are not happend when I have one mysql  
server and all was connecting to that one server. Do You have maybe same  
problems? Do You know what can be a reason and solution for it?  

---  
Best regards  
Sławek Kapłoński  
slawek at kaplonski.pl_______________________________________________  
OpenStack-operators mailing list  
OpenStack-operators at lists.openstack.org  
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