This article is a followup to Matching EC2 Availability Zones Across AWS Accounts written back in 2009. Please read that article first in order to understand any of what I write here.
Since I wrote that article, Amazon has apparently changed the reserved instance offering ids at least once. I haven’t been tracking this, so I don’t know if this was a one time thing or if the offering ids change on a regular basis.
Interestingly, the offering ids still seem to match across accounts and still map to different availability zones, so perhaps they can still be used to map the true, underlying availability zones as the original article proposes.
To document for posterity and comparison, here are my 2009 availability zone offering ids as calculated by the procedure in the above mentioned article:
“Blue” Account (2009):
eu-west-1a 649fd0c8-75d4-4e16-88c7-1ddb83f66062 eu-west-1b 438012d3-0440-480a-9f5c-eb7e55dd5a37 us-east-1a 4b2293b4-1e6c-4eb3-ab74-4493c0e57987 us-east-1b 60dcfab3-a56c-4092-8c90-3677e9da02b7 us-east-1c c48ab04c-c057-457e-a4d8-a0f172f4db2d us-east-1d c48ab04c-7e96-4ea8-9579-d62194490546
“Red” Account (2009):
eu-west-1a 438012d3-0440-480a-9f5c-eb7e55dd5a37 eu-west-1b 649fd0c8-75d4-4e16-88c7-1ddb83f66062 us-east-1a c48ab04c-c057-457e-a4d8-a0f172f4db2d us-east-1b 4b2293b4-1e6c-4eb3-ab74-4493c0e57987 us-east-1c 60dcfab3-a56c-4092-8c90-3677e9da02b7 us-east-1d c48ab04c-7e96-4ea8-9579-d62194490546
And here are the new, 2011-05-25 availability zone offering ids.
“Blue” Account (2011):
eu-west-1a c48ab04c-0bd0-4be9-8db5-a4bad61c6c58 eu-west-1b d586503b-7025-44e8-8487-09907b6b0e7e us-east-1a 438012d3-80c7-42c6-9396-a209c58607f9 us-east-1b 60dcfab3-06bb-4b68-9503-53bf89823b5e us-east-1c ceb6a579-757c-474b-b09b-52c84b605767 us-east-1d 649fd0c8-5d76-4881-a522-fe5224c10fcc
“Red” Account (2011):
eu-west-1a d586503b-7025-44e8-8487-09907b6b0e7e eu-west-1b c48ab04c-0bd0-4be9-8db5-a4bad61c6c58 us-east-1a ceb6a579-757c-474b-b09b-52c84b605767 us-east-1b 438012d3-80c7-42c6-9396-a209c58607f9 us-east-1c 60dcfab3-06bb-4b68-9503-53bf89823b5e us-east-1d 649fd0c8-5d76-4881-a522-fe5224c10fcc
Note: I have excluded the regions and availability zones that Amazon has added since 2009 (quite a few).
Though all of the offering ids have changed since 2009, it appears that the availability zone mappings between these two accounts has remained the same across the years. This is a small sampling and I still think that Amazon could change this, especially for zones where no resources are being used (instances running, EBS volumes created), so don’t depend on it remaining so.
Please let me know if you do any further experimentation or future tracking of these ids. There’s not a ton of practical application, but I still find this interesting.