Re: Postgresql in a Virtual Machine

On 25.11.2013 22:01, Lee Nguyen wrote:
> Hi,
>
> Having attended a few PGCons, I've always heard the remark from a few
> presenters and attendees that Postgres shouldn't be run inside a VM. That
> bare metal is the only way to go.
>
> Here at work we were entertaining the idea of running our Postgres database
> on our VM farm alongside our application vm's. We are planning to run a
> few Postgres synchronous replication nodes.
>
> Why shouldn't we run Postgres in a VM? What are the downsides? Does anyone
> have any metrics or benchmarks with the latest Postgres?

I've also heard people say that they've seen PostgreSQL to perform worse
in a VM. In the performance testing that we've done in VMware, though,
we haven't seen any big impact. So I guess the answer is that it depends
on the specific configuration of CPU, memory, disks and the software.
Synchronous replication is likely going to be the biggest bottleneck by
far, unless it's mostly read-only. I don't know if virtualization will
have a measurable impact on network latency, which is what matters for
synchronous replication.

So, I'd suggest that you try it yourself, and see how it performs. And
please report back to the list, I'd also love to see some numbers!

- Heikki