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Monday
Apr142014

How do you even do anything without using EBS?

In a recent thread on Hacker News discussing recent AWS price changes, seldo mentioned they use AWS for business, they just never use EBS on AWS. A good question was asked:

How do you even do anything without using EBS?

Amazon certainly makes using EBS the easiest path. And EBS has a better reliability record as of late, but it's still often recommended to not use EBS. This avoids a single point of failure at the cost of a lot of complexity, though as AWS uses EBS internally, not using EBS may not save you if you use other AWS services like RDS or ELB.

If you don't want to use EBS, it's hard to know where to even start. A dilemma to which Kevin Nuckolls gives a great answer:

Well, you break your services out onto stateless and stateful machines. After that, you make sure that each of your stateful services is resilient to individual node failure. I prefer to believe that if you can't roll your entire infrastructure over to new nodes monthly then you're unprepared for the eventual outage of a stateful service.

Most databases have replication but you need to make sure that the characteristics of how the database handles a node failure are well understood. Worst case you use EBS, put your state on it, snapshot it regularly, and ship those snapshots to another region because when EBS fails it fails hard.

Also, logs make every machine stateful. Use something like logstash to centralize that state.

If ELB is down in a given region then DNS failover to another region. Assuming you feel comfortable rolling your entire infrastructure monthly, have good images / configuration management, and have the state replicated in the backup region. That or sidestep ELB in your region to a team of stateless load balancers that terminate SSL.

Jeremy Edberg to a question about how to run databases without EBS, says:

By having good replication, either hand rolled or built in.

At Netflix we use Cassandra and store all data on local instance storage. We don't use EBS for databases.

Reader Comments (5)

Would please anyone tell me what the acronym EBS stands for ? I'll wikipedia from there on on my own.

thanks,
Manuel

April 14, 2014 | Unregistered CommenterManuel

I made the same conclusion in my AWS design. I depend on higher stack components for fault tolerance and redundancy. Database hot mirroring, redis mirroring, central configuration and saltstack to make creating new machines trivial.

I just attended the AWS Ninja session in Sydney and lo and behold, this is exactly what they said and is recommended by Amazon. Use transient and not EBS if possible.

I assume EBS is mainly to support existing applications that can't be re-architected.

April 14, 2014 | Unregistered CommenterRob Fowler

EBS is not good, what about ELB? Let's discuss it on Hacker News

April 15, 2014 | Unregistered Commentermikhailov

@Manuel EBS = Elastic Block Store
Its a virtual block device mapped to network storage. It's like iSCSI almost.

April 15, 2014 | Unregistered CommenterDa Xue

John Watson was commenting on twitter that there was an update in their current realtime system and pointed the changes. See the tweet here.

April 29, 2014 | Unregistered Commenternire

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