3 ms·
Ask HN: Does AWS EBS have contradictory availability and durability guarantees?
I'm going over AWS EBS product pages.
* EBS provides an availability guarantee of 99.999% (https://aws.amazon.com/ebs).
* EBS provides a durability guarantee of 99.8-99.9% (https://aws.amazon.com/ebs/details/#AvailabilityandDurability).
I don't follow how these two numbers add up however. If you're losing data %0.1-0.2 of the time, how can you provide availability guarantees that are 99.999%?
Is this because one of the guarantees is dated? Or does AWS consider available as "hey, we lost your data but you can still access EBS"? (doubt it)
I'm asking because I was reading this post (goo.gl/eNhxaj) on HA and Disaster Recovery in Citus Cloud. I thought the author made a mistake in the second or third paragraph, but found that the links actually said the same things.
- misframer 10y agoCould it be that they're only providing 99.999% availability for volumes that haven't failed?
- davismwfl 10y agoThey are two different terms. Availability, the chance when you ask for the data it won't be there, 99.999% chance it will be. Durability, the chance you will loose data and it will never be available is rated at 99.8% chance you won't. Unless I misunderstand something.