EC2 Reserved Instance Offering IDs Change Over Time

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.