Upgrading amazon EC2 m1.large instance to m3.large with mongodb installed

Question

If I were to upgrade an amazon instance, I'd create a snapshot of the image and create the new instance from this image and then upgrade that instance.

My question(s) is related to mongodb and the best way upgrade from a m1.large to a m3.large instance - basically m3's are cheaper and more powerful than the old m1's.

I currently have mongodb running on the m1.large instance backed by 3 EBS Volumes for storage, journalling and logs (essentially the mongodb image config from the MarketPlace).

When i've gone through to setup the new m3.large instance, I noticed that it's not EBS Optimized.

Working with mongodb and the current config, I assume for optimal performance, it's desirable to go the EBS Optimized route - if that's the case, the best upgrade path is to go for m3.xlarge? Would I hit a big performance penalty if I went with a m3.large?

And lastly....after taking a snapshot of an image (specifically an image backed with EBS Volumes), does the new image take that same config setup? IE The new image will be backed by the same volumes?

I know I can stop and start the current instance, but I want to minimise any downtime.

Any help appreciated!

Answer 1

Firstly, you don't need to create an entire new instance, snap the EBS volumes of the old one, and attach the copies. If you're doing this to try to avoid service interruption, what happens when you switch the EIP from the old to the new instance? Yep - service interruption.

Just stop the m1, reset it to m3, and start. There will be an outage, of course, but you'll be back in less than 5 minutes and you've saved yourself a chunk of work replicating volumes.

As for EBS Optimised - do you really need that? Do you understand what it means, and what the consequences of NOT having it on the new instance are? If the answers to both are YES, then of course pick an m3 (or larger) instance type that supports it. If NO, research until you know what the feature gives you and whether you actually need it (you pay more with it active - don't spend more than you actually need to).