Re: HA Setup Review

On Tue, Apr 30, 2024 at 3:41 AM akshay polji <akshay(dot)polji(at)gmail(dot)com> wrote:

> Hello Team,
>
> I am looking for some feedback on the HA Setup that we are finalizing for
> running our business critical workloads.
>
> We are planning to follow this Setup,
> https://www.pgpool.net/docs/42/en/html/example-cluster.html
>
>
> - Basically a 3 node PostgreSQL Cluster, running 3 processes i.e.
> PostgreSQL DB, PGPool and WatchDog.
> - These 3 nodes will be distributed across 3 availability zones/data
> centers for resilience and use a synchronous replication between
> Primary and Stand-by.
>
> You're describing HA+DR, not just HA,

Also, I wouldn't do synchronous replication across the WAN. Not only is the
latency too high for decent performance, but any fault in the network
freezes the DB.

> - Synchronous option will be Any One, so that the DB availability is
> not impacted if 1 Stand-by is down for even planned outage i.e. Patching of
> DB or Virtual Machine.
>
> You can switch from async to sync replication just before patching, and
then switch back to async when it's completed.

That's pretty much what we do for HA, except only two DB instances (but
still three PgPool instances), and they are local and asynchronously
replicated. DR is handled by VMware SRM.

Watchdog and heartbeat are built into PgPool. Is that what you're using
for WD and HB?