"Currently, Netflix uses a service called "Chaos Monkey" to simulate service failure. Basically, Chaos Monkey is a service that kills other services. We run this service because we want engineering teams to be used to a constant level of failure in the cloud. Services should automatically recover without any manual intervention. We don't however, simulate what happens when an entire AZ goes down and therefore we haven't engineered our systems to automatically deal with those sorts of failures. Internally we are having discussions about doing that and people are already starting to call this service "Chaos Gorilla"."
I am wondering how they could simulate the loss of an AZ. Any ideas?
"One of the first systems our engineers built in AWS is called the Chaos Monkey. The Chaos Monkey’s job is to randomly kill instances and services within our architecture. If we aren’t constantly testing our ability to succeed despite failure, then it isn’t likely to work when it matters most – in the event of an unexpected outage."
Sounds like Chaos Monkey distributes his chaos randomly.
> I am wondering how they could simulate the loss of an AZ. Any ideas?
They could instrument whatever library they use to interact with AWS and make it report failures or fail to respond to "create new instance"-like commands.
There are several ways to do it. Kill all the instances. Use a firewall to blackhole all the instances. Use traffic shaping to degrade the latency or packet loss of all the instances.
I concur. I feel like I learned a lot just reading that article. Makes me feel much better about Netflix, even though I already was a huge fan. Glad to see they are on top of their technology.
Interesting that they're not using EBS to provide durable storage for Cassandra, but instead using S3 (along with S3-backed, or "ephemeral storage", AMIs). I wonder if that means they're batching up and writing their database logs to S3, plus running enough instances across AZs that it's generally okay to keep everything in memory even when an instance or two fails.
Anyone have any experience running a NoSQL datastore in this fashion?
They're probably using the local ephemeral drives for Cassandra storage rather than S3. I'm guessing they're then moving snapshots into S3 or elsewhere.
Yet another great post. Seems like they rely on simpledb a lot.
Scaling up/down webserver-LB-appserver stack is the easiest part. Managing db(sql/no-sql) is a juggle. It is great that nflx avoided the db hosting them selves by adopting simpledb.
One common thing among other players that went down during the aws outage:
quora - mysql
4sq - mongodb
reddit - postgre
In the discussions after the AWS outage, a lot of people seemed to be assuming that Netflix was able to stay up because they had the $$$$ to spread their service across multiple regions, not just AZ's.
It looks like that wasn't the case, they stay in one region but avoid EBS like the plague(among other things).
In a way this outage can turn out financially positive for Amazon as more and more customers will start using multiple regions instead of just one region. In addition to multiple instances that customers will need to bring up, they will be paying for the inter-region data transfer costs. This should compensate for the customers they will lose because of this outage and new customers who will choose some other cloud.
18 comments
[ 4.0 ms ] story [ 43.1 ms ] threadI am wondering how they could simulate the loss of an AZ. Any ideas?
Kill all instances in an AZ?
Sounds like Chaos Monkey distributes his chaos randomly.
They could instrument whatever library they use to interact with AWS and make it report failures or fail to respond to "create new instance"-like commands.
It's like a lessons learn. I hope more companies do this.
Anyone have any experience running a NoSQL datastore in this fashion?
http://www.mail-archive.com/user@cassandra.apache.org/msg110...
Scaling up/down webserver-LB-appserver stack is the easiest part. Managing db(sql/no-sql) is a juggle. It is great that nflx avoided the db hosting them selves by adopting simpledb.
One common thing among other players that went down during the aws outage: quora - mysql 4sq - mongodb reddit - postgre
It looks like that wasn't the case, they stay in one region but avoid EBS like the plague(among other things).