Failed to create new routing session. Couldn't find eligible candidate server.

[Rizal E S]

Hi all, 

I got error log, 

2015 02/03 11:54:12  Error : Failed to create new routing session. Couldn't find eligible candidate server. Freeing allocated resources.

2015 02/03 11:54:12  Error : Failed to create router client session. Freeing allocated resources.

and this is my MaxScale.cnf file

[maxscale]

threads=4

[Galera Service]

type=service

router=readconnroute

router_options=synced

servers=dbserver1

user=maxuser

passwd=maxpwd

[Debug Interface]

type=service

router=debugcli

[Galera Listener]

type=listener

service=Galera Service

protocol=MySQLClient

port=4306

[Debug Listener]

type=listener

service=Debug Interface

protocol=telnetd

port=4442

[dbserver1]

type=server

address=192.168.56.221

port=3306

protocol=MySQLBackend

[dbserver2]

type=server

address=192.168.56.223

port=3306

protocol=MySQLBackend

[dbserver3]

type=server

address=192.168.56.223

port=3306

protocol=MySQLBackend

I acces from 192.168.56.14,   mysql -umaxuser -p -h 192.168.56.14 -P 4306

ERROR 1045 (2800): failed to create new session

I was enabled user to access in mariadb galera gluster

+---------+-----------------+

| user    | host            |

+---------+-----------------+

| rizal   | %               |

| root    | 127.0.0.1       |

| maxuser | 192.168.56.14   |

Anyone know how to fix this problem, thank you very much. 

[Markus Mäkelä]

Hi,

You seem to be missing the monitor module for galera clusters which
means that MaxScale has no way of knowing the state of the servers. I'm
assuming you have a galera cluster running on the three servers.

You can fix this by adding the following to your configuration file:

[Galera Monitor]
type=monitor
module=galeramon
servers=dbserver1dbserver2,dbserver3
user=maxuser
passwd=maxpwd
monitor_interval=1000

If you are not using galera, the mysqlmon module should be used instead
of the galeramon module.

An example configuration and explanations about the modules can be found
from the MaxScale_template.cnf file in the etc/ folder of the
installation directory (here's a link to it on GitHub:
https://github.com/mariadb-corporation/MaxScale/blob/develop/server/MaxScale_template.cnf).

Markus

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[Rizal E S]

Thanks Markus, It works, I can insert and update mariadb galera cluster now. But I checking error log I found this :

2015 02/03 12:43:06  Error : Unexpected parameter 'monitor_interval' for object 'Galera Monitor' of type 'monitor'.

2015 02/03 12:43:06  Error : The service 'Debug Interface' is missing a definition of the servers that provide the service.

I have 3 node of mariadb galera cluster. is possible configure maxscale to make node1 for only Write, and node 2, 3 only for read.? I think node1 only for write, if node1 is down, then node2 can write.  Example create database only to node1 and galera replicate the database to node2 and node3. I stil use haproxy to balancing mariadb galera cluster, but if node1 2 3 can write/insert sometimes the database can deadlock. Any solutions to avoid deadlock with MaxScale? 

Thank you very much. 

[Markus Mäkelä]

Hi,

The errors are not critical but the one about the unexpected parameter
should not have appeared as far as I know. The Debug Interface error is
generated because it has no servers, this is a known bug about this
module.

You can use the readwritesplit router to split read/write queries to
different servers. The way it works with a galera cluster is that it
sets one node as the "master" node where all writes go and it balances
the read queries between the other nodes. You can do this by replacing
the Galera Service with the following one:

[Galera Service]
type=service
router=readwritesplit
servers=dbserver1,dbserver2,dbserver3
user=maxuser
passwd=maxpwd
max_slave_connections=100%

The max_slave_connections determines the number of "slave" nodes each
session uses for routing read queries. Setting it to 100% spreads the
read load over all the nodes. You can look up the other parameters for
the readwritesplit router from the template configuration file I linked
before.

Markus

[Rizal E S]

Thanks you for your attention,

I was change MaxScale.cnf

[Galera Service]
type=service
router=readwritesplit
servers=dbserver1,
dbserver2,
dbserver3
user=maxuser
passwd=maxpwd

the other config still same with MaxScale.cnf in above

I found error log on maxscale host

2015 02/03 14:25:08 Error : Couldn't find suitable Slave from 1 candidates.
2015 02/03 14:25:08 Error : Couldn't find suitable Master from 1 candidates.
2015 02/03 14:25:08 Error : Failed to create router client session. Freeing allocated resources.

and in client host error like this

mysql -umaxuser -p -h 192.168.56.14 -P4306

Enter password:

ERROR 1045 (2800): failed to create new session

I was make node1 to master, and node 2 & 3 to slave.

Thanks for help.