I'm going to install Percona XtraDB Cluster, and I have two questions about it:

1- Is it the last step? https://www.percona.com/doc/percona-xtradb-cluster/LATEST/verify.html

Or installing ProxySQL is mandatory? I have only 3 nodes and not planning to add an extra node only for ProxySQL! And I think I don't even need it, my round-robin load-balancer is sending the requests to these servers randomly (without health controlling).

So if a node is down it can't even read/write to the DB. in a nutshell, my application nodes are the same as my DB nodes, and a load-balancer in front of them, So I think I don't need ProxySQL, Am I?

2- What happens if all 3 nodes are down together, I think if this situation happens in a common Group Replication of MySQL, all the cluster collapses and all nodes are being removed from the cluster and we need to reconfigure the cluster manually again, Is the same problem exists in PXC or not?

1 Answer 1

  1. No, installing ProxySQL is not mandatory
  2. Do you mean all three nodes close down suddenly rather than close down gracefully? What version of Percona XtraDB Cluster are you using? If it is a version 5.6.19 or later, then the nodes will read the last state on startup and will try to restore primary component once all the members again start to see each other. This makes the PXC cluster to automatically recover from being powered down without any manual intervention. This information came from https://www.percona.com/blog/2014/09/01/galera-replication-how-to-recover-a-pxc-cluster/ and you may find other useful blogs around this subject and/or webinars on the Percona site.

Disclosure: I am from Percona

  • Yes, I'm using the latest version and I mean closing down suddenly, like losing power supply. Or imagine a situation when all nodes are VMs in a single dedicated server, so if something happens for that Dedicated servers all nodes are off! P.S: As you said you're from Percona would you please check my comments in this topic, I haven't got answered yet: dba.stackexchange.com/questions/216949/…
    – behnamy01
    Commented Sep 10, 2018 at 16:35
  • Yes, I'll look. Generally, you'll get better responses from the Percona community forum as not all of the Percona engineers respond off-site. We are always happy to update the answers on the 'external' sites once an issue is resolved.
    – greenweeds
    Commented Sep 14, 2018 at 8:21

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