TurnKey Linux Virtual Appliance Library

Why is S3 backing better than EBS?

jeremiah.snapp's picture

The following facts lead me to believe that many users run S3 backed instances and even prefer them over EBS backed instances.

  1. Since S3 was originally the only option Amazon had for backing an instance
  2. Until recently TurnKey only worked with S3 backing even though Amazon had EBS backing available
  3. S3 backing is said to be more performant than EBS backing  - actually Amazon states here that "The latency and throughput of Amazon EBS volumes is designed to be significantly better than the Amazon EC2 instance stores in nearly all cases."

With that said I still can't understand how you could risk losing data between the last backup and the moment an S3 backed instance terminates.  All database changes, logs, etc would get lost.  I know you could just say "Well, why would you terminate the instance?"  That's fine but what if Amazon bugs out and terminates it by accident.  Or what if your software bugs out and forces a termination.  Those may be very unlikely occurences but I find it difficult to believe so many people are willing to take that risk.

I feel like I'm probably just missing something so please help me figure out what it is I'm missing.  I'd like to setup my first TKLHUB server very soon and I need to understand this before deciding which backing I'll use.

Thanks in advance,
Jeremiah

Jeremy Davis's picture

Yes there is risk

But from my understanding of S3, that because of the redundancy provided by Amazon, the risk is far lower than local hardware failure. So as long as you have a recent backup, your data is safer than running on a local machine.

I guess as far as troubleshooting a failed instance goes there could be an issue and EBS backed instances may be superior as you would be able to check the logs just prior to the instance termination.

Considering the performance of S3 vs EBS have a look at Liraz's comments here

. He also speaks about data storage reliability (S3 vs EBS) briefly in the blog post.

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