Re: Postgresql in a Virtual Machine

On Nov 26, 2013, at 9:24 AM, Craig James wrote:

> So far I'm impressed by what I've read about Amazon's Postgres instances. Maybe the reality will be disappointing, but (for example) the idea of setting up streaming replication with one click is pretty appealing.

Where did you hear this was an option? When we talked to AWS about their Postgres RDS offering, they were pretty clear that (currently) replication is hardware-based, the slave is not live, and you don't get access to the WALs that they use internally for PITR. Changing that is something they want to address, but isn't there today.

That said, we use AWS instances to run Postgres, and so long as you use their Provisioned IOPS service for i/o and size your instances appropriately, it's been pretty good. Maybe not the most cost-effective option, but you're paying for the service to not have to worry about stocking spare parts or making sure your hardware is burned in before use. And AWS makes it easy to add regional or even global redundancy, if that's what you want. (Of course that costs even more money, but if you need it, using AWS is a lot easier than finding colos around the world yourself.)

Like many have said, the problem of using VMs for databases is that a lot of VM systems try to over-subscribe the hardware for more savings. That works for a lot of loads but not a busy database. So just make sure your VM isn't doing that to you, and most of the performance argument for avoiding VMs goes away.