Unavailable Availability Zones on Amazon EC2

I’m taking a class about using Chef with EC2 by Florian Drescher today and Florian mentioned that he noticed one of the four availability zones in us-east-1 is not currently available for starting new instances.

I’ve confirmed this in my own AWS accounts and found that one of the three availability zones in us-west-1 is also unavailable in addition to one of the four availability zones in us-east-1.

Here’s the error I get when I try to start an instance in the availability zone using an old AWS account:

Client.Unsupported: The requested Availability Zone is no longer supported. Please retry your request by not specifying an Availability Zone or choosing us-east-1d, us-east-1a, us-east-1b.

When I use an AWS account I created two days ago, I don’t even see the fourth availability zone at all:

$ ec2-describe-availability-zones --region us-east-1
AVAILABILITYZONE    us-east-1b  available   us-east-1   
AVAILABILITYZONE    us-east-1c  available   us-east-1   
AVAILABILITYZONE    us-east-1d  available   us-east-1   

The exact name of the unavailable availability zones will vary between EC2 accounts. You can read more about that here:

Matching EC2 Availability Zones Across AWS Accounts

The availability zones that are unavailable in my AWS accounts map to the following identifiers using the method described in the above article:

us-east-1x ceb6a579-757c-474b-b09b-52c84b605767
us-west-1x e5a2ff3b-79b4-4217-8c93-ebf1d633dd6e

If my guess is correct based on old accounts I have, I believe these may be the oldest (original) availability zones in their respective regions.

Has there been any communication from Amazon about unsupported availability zones? Is this temporary or permanent? When I searched Google for the above error, I got back one result in Japanese and it appears to be somebody asking what the error is.

No longer supporting an availability zone in EC2 is something that Amazon is allowed to do under the EC2 SLA, especially with the way that they seem to phase them out. The SLA does not kick in until two availability zones are completely unavailable and “unavailable” includes your existing instances having no external connectivity. This is one reason we try to architect services with the ability to quickly move resources from one availability zone to another.

I’d love to hear if other people are able to start instances in these availability zones. Please also mention if you already have instances running in those zones.

Update 2011-08-06: According to a post in May from Amazon this seems to be a normal part of how AWS grows in an orderly manner, and if you already have instances running in a zone, you should be able to continue running instances in that zone. It isn’t clear to me how quickly you might lose a zone after your last remaining instance is stopped or terminated, but according to one user it sounds like it might be nearly immediate.