Can you cite something about this? I can't find anything, except confirming that's not true [1].
Your profile says you work at AWS so I assume you have inside info on this. Perhaps you could also explain why this change would get made? I always considered it pretty smart to do - With consistent machines, wouldn't the lowered-lettered zones get significantly more traffic? Most of my deploys go to a+b or a+b+c (and I have various services running in 5 different regions, I think). I'm not sure I even have anything running in more than 3 AZs, and thus never use AZ d, for example. I'm positive I'm not alone in that style of setup.
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EDIT: Just comparing two accounts I have (which are linked, if that makes a difference), it does in fact look like most regions do have the same mappings. us-east-1 and us-west-2 are definitely different, but all the other ones I checked seem to be the same. They're not all consistent (a=1, b=2, etc) though, but for example, these are the same on both accounts:
AZ Name AZ ID
eu-central-1a euc1-az2
eu-central-1b euc1-az3
eu-central-1c euc1-az1
eu-west-3a euw3-az1
eu-west-3b euw3-az2
eu-west-3c euw3-az3
ap-south-1a aps1-az1
ap-south-1b aps1-az3
ap-south-1c aps1-az2
I still find this silly. Anyone following basic examples or deploying single-AZ is going to provision stuff in the "a" zone. That zone must be 10x bigger than "c" in any given region. It blows my mind.
[1] https://aws.amazon.com/premiumsupport/knowledge-center/vpc-m...
Your profile says you work at AWS so I assume you have inside info on this. Perhaps you could also explain why this change would get made? I always considered it pretty smart to do - With consistent machines, wouldn't the lowered-lettered zones get significantly more traffic? Most of my deploys go to a+b or a+b+c (and I have various services running in 5 different regions, I think). I'm not sure I even have anything running in more than 3 AZs, and thus never use AZ d, for example. I'm positive I'm not alone in that style of setup.
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EDIT: Just comparing two accounts I have (which are linked, if that makes a difference), it does in fact look like most regions do have the same mappings. us-east-1 and us-west-2 are definitely different, but all the other ones I checked seem to be the same. They're not all consistent (a=1, b=2, etc) though, but for example, these are the same on both accounts:
I still find this silly. Anyone following basic examples or deploying single-AZ is going to provision stuff in the "a" zone. That zone must be 10x bigger than "c" in any given region. It blows my mind.[1] https://aws.amazon.com/premiumsupport/knowledge-center/vpc-m...