Why only 2 KeepAliveD?

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Aviram Alter

• February 18, 2017 18:56

Any reason it is only possible to deploy 2 Keepalived instances in Clustercontrol? What if I want a VIP for 3 HAproxy nodes...?

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  Ashraf Sharif

  • February 19, 2017 04:54

  Hi Aviram,

  ClusterControl implements Keepalived's virtual IP address with master-backup approach, which has the least requirement of two HAproxy instances. Only one HAproxy instance holds the VIP in a time. If you had 3 HAProxy instances, and the first one went down, the VIP would be failed over to haproxy #2 (the backup instance). Once haproxy #1 got back up, the VIP would be failed back to haproxy #1 (the master instance). Haproxy #3 won't be used unless #1 and #2 go down at a same time.

  In most cases, having two HAproxy instances is suffice in production environment (provided the HAproxy instances live in separate physical hosts).

  Regards,
  Ashraf

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  Ashraf Sharif

  • February 19, 2017 05:03

  Hi Aviram,

  To answer your question, you can just install Keepalived manually on HAproxy #3 and configure /etc/keepalived/keepalived.conf with similar configuration as the rest. Ensure on #3, the state is BACKUP, holds the same VIP and the unicast peer list is updated accordingly.

  Regards,
  Ashraf

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  Aviram Alter

  • February 26, 2017 11:43
  • Edited

  Thanks

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