[pgpool-general: 7549] Re: VIP with one node

[Tatsuo Ishii]

> Dear all,
> 
> I have fairly common 3-node cluster, with each node running a PgPool
> and a PostreSQL instance.
> 
> I have set up priorities so that:
>   - when all 3 nodes are up, the 1st node is gonna have the VIP,
>   - when the 1st node is down, the 2nd node is gonna have the VIP, and
>   - when both the 1st and the 2nd nodes are down, then the 3rd node
> should get the VIP.
> 
> My problem is that when only 1 node is up, the VIP is not brought up,
> because there is no quorum.
> How can I get PgPool to bring up the VIP to the only remaining node,

There's no way to do that.

> which still could and should serve requests?

No, because it's dangerous. Think about a split brain scenario: node A
loses connection to node B and c. In this case node A loses the
quorum, while node B and C have the quorum and will keep the VIP. If
we allow the VIP to node A, there are 2 VIPs are up. We surely want to
avoid it.

Best regards,
--
Tatsuo Ishii
SRA OSS, Inc. Japan
English: http://www.sraoss.co.jp/index_en.php
Japanese:http://www.sraoss.co.jp