Compare with SoftLayer which has decided to charge through the nose for their RAM upgrades: going from 16 to 64GB RAM on their E5 servers is an additional $1200/month.
They're far more expensive than e.g. Rackspace there for some reason.
I haven't looked at SoftLayer's offerings re: RAM but the most important thing to note with Hetzner is that only some of their dedicated machines have error-correcting code (ECC) memory. Hetzner's 16GB machine[1] (89 Euros/month) has ECC memory for example.
Whilst this might not sound like an enormous issue, DRAM errors are surprisingly common in real deployments[2] and can result in scary things happening to your data.
If you're using a machine without ECC memory make sure you're prepared to deal with any possible issues that might arise, especially if it will impact your core business.
How common DRAM errors are is very unclear. The numbers in that paper are astronomically high, but other sources have published numbers that are 30x or 100,000x or literally 10,000,000x lower.
I don't think there's a confirmed source, but there's certainly indications, for example, an AWS post that they use ECC memory for the GPUs in their cluster GPU instance
Given that they list both the standard memory and GPU memory next to each other, but only put ECC next to the GPU memory, it seems relatively likely to me that the standard server memory is not ECC.
I was not able to find Amazon declaring that they don't, but neither do they say anywhere that they do. For example they describe the hardware specs here: http://aws.amazon.com/ec2/instance-types/ If they did have ECC RAM it is unlikely that they would keep it secret, especially given that ECC RAM can be twice as expensive.
I think it is a good idea to architect your system under the assumption that once a year, some theif is going to sneak into the data center and make off with an entire server. Just one, but the whole server will then die horribly in a fire after a shoot-out with the police.
Lots of things can happen, you should have a higher level of replication such that you can handle a whole server going poof, not just a single bit going poof.
The cost of ECC at Hetzner-- the cheapest provider out there- is about half an additional server. So, buy three servers without ECC for the price of two servers with ECC, and replicate your data three times (and triple your bandwidth, horsepower, etc.)
This is not hard with platforms like Riak which are distributed homogenous clusters of nodes.
And if your service isn't built like that, then really it should be. (IMNSHO, of course.)
ECC Does nothing to prevent your server from dying in a fire after that police chase, either. However, replication is an effective solution to the problem you describe:
Whenever data is read, you read from more than one replica, and then compare them. If one of them has been corrupted, its hash won't match and you'll know it. You can then write out the correct data to the node with the error. This is very easy in systems like Riak.
They're far more expensive than e.g. Rackspace there for some reason.