They did this to stop people from overloading us-east-1a.
It was fine, until there started to be ways of wiring up networks between accounts (eg PrivateLink endpoint services) and you had to figure out which AZ was which so you could be sure you were mapping to the the same AZs in each account.
I built a whole methodology for mapping this out across dozens of AWS accounts, and built lookup tables for our internal infrastructure… and then AWS added the zone ID to AZ metadata so that we could just look it up directly instead.
It was for spreading load out. If someone was managing resources in a bunch of accounts and always defaulted to, say, 1b, AWS randomized what AZs corresponded to what datacenter segments to avoid hot spots.
The canonical AZ naming was provided because, I bet, they realized that the users who needed canonical AZ identifiers were rarely the same users that were causing hot spots via always picking the same AZ.
Almost everyone went with 1a, every time. It causes significant issues for all sorts of reasons, especially considering the latency target for network connections between data centres in an AD
They did this to stop people from overloading us-east-1a.
It was fine, until there started to be ways of wiring up networks between accounts (eg PrivateLink endpoint services) and you had to figure out which AZ was which so you could be sure you were mapping to the the same AZs in each account.
I built a whole methodology for mapping this out across dozens of AWS accounts, and built lookup tables for our internal infrastructure… and then AWS added the zone ID to AZ metadata so that we could just look it up directly instead.
It was for spreading load out. If someone was managing resources in a bunch of accounts and always defaulted to, say, 1b, AWS randomized what AZs corresponded to what datacenter segments to avoid hot spots.
The canonical AZ naming was provided because, I bet, they realized that the users who needed canonical AZ identifiers were rarely the same users that were causing hot spots via always picking the same AZ.
Almost everyone went with 1a, every time. It causes significant issues for all sorts of reasons, especially considering the latency target for network connections between data centres in an AD
Presumably it would help ensure that everyone selecting us-east-1a in their base configs didn't actually all land in the same AZ.
Yeah this one drove me crazy