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Are there any known differences between the different US East availability zones? I've noticed 1e is new on the list. Does that mean that the underlying hardware is newer and the EC2 instances potentially have better performance?

It seems that I lock myself into a particular AZ when creating EBS volumes so I wanted to know if there's any "inside knowledge" that might help my decision.

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up vote 4 down vote accepted

Availability zone identifiers (us-east-1a, us-east-1b, etc.) are different for every account. So us-east-1e may not be the same as us-east-1e for someone else.

I think part of the reason for this is to avoid situations just like this: certain AZ's getting bad (or good) reputations and having people flock away (or toward) certain AZ's.

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Wow! Bizarre. So why the limitation that my EBS volumes can only be attached to instances in the same sub-AZ? What is the point of having the sub-identifiers at all? why not just "us-east-1" for everything? – Nic Cottrell Jan 19 '13 at 14:21
What are you calling a "sub-AZ?" us-east-1 is a region and us-east-1e is an availability zone inside that region; each availability zone is typically a different physical facility. If EBS volumes weren't required to be in the same AZ as the instance, latencies and performance would suffer.… – Michael - sqlbot Jan 19 '13 at 17:46
Each AZ is a distinct facility. The identifiers are used to coordinate multiple AWS resources so as to minimize latencies. For example, if you have one instance as a front-end web server, and another as a back-end database, you may want them to be in the same facility so that communication between them is as fast as possible. – Matt Houser Jan 19 '13 at 20:01
An Availability Zone is not necessarily a single data center / facility. The us-east-1 region has a handful of availability zones, but is comprised of over ten data centers (and probably growing). – Eric Hammond Jan 21 '13 at 18:48
Thanks all for the clarifications! – Nic Cottrell Jan 22 '13 at 7:42

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