Message-ID: <5293B2F4.10102@dunslane.net>
Date: Mon, 25 Nov 2013 15:28:36 -0500
From: Andrew Dunstan <andrew@dunslane.net>
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To: Heikki Linnakangas <hlinnakangas@vmware.com>
CC: Lee Nguyen <leemobile@gmail.com>, pgsql-performance@postgresql.org
Subject: Re: Postgresql in a Virtual Machine
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On 11/25/2013 03:19 PM, Heikki Linnakangas wrote:
> 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!
>
>


Yeah, and there are large numbers of public and/or private cloud-based 
offerings out there (from Amazon RDS, Heroku, EnterpriseDB and VMware 
among others.) Pretty much all of these are VM based, and can be 
suitable for many workloads.

Maybe the advice is a bit out of date.

cheers

andrew


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