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Percona XtraDB Cluster

GarciaGarcia EntrantCurrent User Role Beginner
Hello, sorry for my English, there is such a problem, I configured Percona XtraDB Cluster on 3 servers, everything is working fine now, but how do I look at the time delay of the slave from the master? If I'm watching now
mysql -e "show slave status\G"
then I get nothing from this documentation https://www.percona.com/blog/2014/05/02/how-to-identify-and-cure-mysql-replication-slave-lag/ swears at
Detected value is empty; something failed?  Trigger exit status: 0
Seconds_Behind_Master parameter is not defined.
How can I see the delay?

Comments

  • przemekprzemek Percona Support Engineer Percona Staff Role
    Hello,

    PXC uses completely different replication technology then normal MySQL, hence "show slave status\G" is not supposed to give any output here.
    If you want to check the replication status, take a look at
    show status like 'ws%';
    

    Check our documentation for more details: https://www.percona.com/doc/percona-xtradb-cluster/LATEST/index.html
  • GarciaGarcia Entrant Current User Role Beginner
    Thanks for the answer, I understand it, but what parameter is responsible for the delay between the slave of the master? wsrep_flow_control_paused_ns or wsrep_flow_control_paused ? Or in general another parameter?
  • przemekprzemek Percona Support Engineer Percona Staff Role
    The wsrep_flow_control_paused_ns is rather to monitor total time when cluster is paused due to Flow Control. To find out which node is "lagging" you should check it's wsrep_local_recv_queue and wsrep_flow_control_sent.
    Replicaiton delay in Galera is not really measured in seconds but in number of transactions waiting to be applied.

    More information on that topic:
    https://www.percona.com/blog/2013/05/02/galera-flow-control-in-percona-xtradb-cluster-for-mysql/
  • GarciaGarcia Entrant Current User Role Beginner
    Thanks again for the answer, now I have such parameters
    server 1
    wsrep_local_recv_queue  0
    wsrep_flow_control_sent 0
    
    server 2
    wsrep_local_recv_queue  0
    wsrep_flow_control_sent 2743050
    
    server 3
    wsrep_local_recv_queue  0
    wsrep_flow_control_sent 22794
    

    Whether it is possible somehow to monitor these parameters wsrep_local_recv_queue and wsrep_flow_control_sent through a zabbix, I adjusted monitoring under this documentation https://www.percona.com/doc/percona-monitoring-plugins/LATEST/zabbix/index.html

    But to which value should these parameters be wsrep_local_recv_queue and wsrep_flow_control_sent?
  • GarciaGarcia Entrant Current User Role Beginner
    Prompt if under this documentation https://www.percona.com/doc/percona-monitoring-plugins/LATEST/zabbix/index.html there is an item MySQL.slave-lag this that that is necessary for me? Or you still have to watch wsrep_local_recv_queue and wsrep_flow_control_sent?
  • jriverajrivera Percona Support Engineer Percona Staff Role
    Since the templates in Zabbix are copied from Cacti ones there should be one for PXC- Galera Replication Queues
    https://www.percona.com/doc/percona-monitoring-plugins/1.1/cacti/galera-templates.html
  • GarciaGarcia Entrant Current User Role Beginner
    Parameters and graphs in zabbix I can configure myself, but I need to understand what to set up? If Percona XtraDB Cluster does not have the Seconds_Behind_Master parameter, then I need to take the parameters wsrep_local_recv_queue and wsrep_flow_control_sent, but how can you tell by these parameters that there is a delay?
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