> All of our Cassandra nodes are now using only local disk, and we hope to have all of postgres on local disk soon.
Since local disk is temporary and can be lost any second, don't they still have to use EBS for persistence?
Since local disk is temporary and can be lost any second, don't they still have to use EBS for persistence?
EBS is a pretty bad product regarding reliability and consistency of performance unfortunately, it's better to design your system without it.
If you can't use any persistent storage, then these machines become pure processing nodes. Which in this case, I feel like it would be better to not design your system with EC2 at all. :-(
To me having EBS made EC2 a very powerful solution compared with their competitors. Not having durable and consistent EBS otherwise makes no point in differentiation and serves purely as non-functional fluff we end up paying extra for.
My general take on this issue is that if you're running your app on EC2 and your persistence medium is something that's also on EC2, you really have no ideal high availability scenario. Of course, even in my case, if SimpleDB and S3 go down, I'm still in trouble, but at least I have the option of throwing Akamai in front of it.