Zone downtime still falls under an AWS SLA so you know about how much downtime to accept and for a lot of businesses that downtime is acceptable.
- Is it worth to spend 20% more on IT to keep our site up 99.99% vs 99%?
- Is it worth to have 3 suppliers for every part that our business depends, with each of them being contracted to be able to supply 2x more, in case other supplier has issues? And pay a big premium for that?
- Is it worth to have offices across the globe, fully staffed and trained to be able to take on any problem, in case there's big electrical outage/pandemic/etc in other part of the world?
I'm not saying that some of those outages aren't results of clowny/incompetent design. But "site sometimes goes down" can be often a very valid option.
Depending on the size of the company it can be simple or hard. Most companies that need this are not huge. Things like RDS, Elasticache, ECR and Secrets have multi AZ integrated so not hard to do it. If you operate on ECS or EKS it's pretty straightforward to boot up nodes and load balancers in another AZ.
Maybe you have a system that requires more hands on work and want to explain your point of view? I don't appreciate the snarky responses tho.
To them it's much easier to communicate "Hey, our customer service is going to be degraded on the second saturday in october, call on monday" to their customers 1-2 month in advance, prepare to have the critical information without our system, and have agents tell people just that.
This has really started to change my thoughts of how to approach, e.g. a major postgres update. In our case, it's probably the better way to just take a backup, shutdown everything, do an offline upgrade and rebuild & restore if things unexpectedly go wrong. We can totally test the happy case to death, and if the happy case works, we're done in 2 hours for the largest systems with minimal risk. 4 hours if we have to recover from nothing, also tested.
And you know, at that point, is it really economical to spend weeks to plan and weeks to test a zero downtime upgrade that's hard to test, because of load on the cluster?
However, in my experience, the people doing the calculations on that risk have no incentive to cover it. Their bonus has no link to the uptime and they can blame $INFRA for the lost millions and still meet their targets and get promoted / crosshired.
The people who warned them and asked for funding are the ones working late and having conf calls with the true stakeholders.
People are just unaware, and probably making bad calls in the name of being "portable".
I'm curious who these web companies are.
Use something like Lambda and you get multi-az for free.
https://docs.aws.amazon.com/lambda/latest/dg/security-resili...
Dynamo is another service that wouldn't be impacted as it is multi-az.
Getting postgres RDS multi-region would require the extra couple of lines in your CDK, but is fairly straightforward.
At least 1 cluster had a node on “affected” hardware (per AWS). Aurora failed to failover properly and the cluster ended up in a weird error state, requiring intervention from AWS. Could not write to the db at all. This took several hours to resolve.
All that to say that it’s never straightforward. In today’s event, it was pure luck of the draw as to whether a multi-AZ Aurora cluster was going to have >60 seconds of pain.
That SaaS has been running Aurora for years and has never experienced anything similar. I was very surprised when I heard the cluster was in a non-customer-fixable state and required manual intervention. I’ve shilled Aurora hard. Now I’m unsure.
Thank goodness they had an enterprise support deal or who knows if they’d still have issues now.
Want GKE to run multi-zone, or Spanner to run multi-region, just check a box (and insert coin).
Not all systems require high availability. Some systems are A-OK with downtime. Sometimes, I'm perfectly fine with eventual consistency. You really do have to look at the use-cases and requirements before making sweeping staements.
Where did legacy apps come from?
> Some systems are A-OK with downtime.
And those ones would not have cared about this outage. Your point isn't that clear.
By your last sentence, it appears you agree with me.
If you meant to say that your statement only applies to cloud architects who are attempting to maintain an uptime SLA with multi-az/region redundancy, then sure, AWS has lots of levers you can pull and those complaining really should spend some time studying them.
As for legacy applications, I would not have brought up them up at all if you hadn't suggested pushing things into lambdas as a solution to multi-az. Once again, there are many many situations where this is not appropriate. Not everything is greenfield, and re-architecting existing applications in an attempt to shoehorn it into a different deployment model seems a bit much. Unless I'm misunderstanding what you meant.
I also disagree that it is inherently more costly to run a service in multiple locations.
Let's say your website requires 4 application servers, you can then tolerate a single AZ failure by using 5 application servers and spreading them among 5 AZs.
Going by your example, If your website requires 1 application server, to tolerate a single AZ failure, it requires you to double the number of application servers.
Example - we have a service that used Kafka in the affected region that went down. Our primary kafka instance (R=3) survived but this auxiliary one failed and caused downtime. There's no way around this other than doubling the cost.
For a single server deployment you can still reduce your downtime (with minimal costs) by having the ASG redeploy into another AZ on a failed health check.
*: https://commons.wikimedia.org/wiki/File:Postgresql_elephant....
It's not just a single instance too, there's generally a lot more infrastructure (db servers, app servers, logging and monitoring backends, message queues, auth servers... etc)
(And checkbox-easy is sweeping edge cases and failure modes under the rug)
its more expensive to have more things and it’s more expensive to have more complicated things that are also complex. And things that can fall over are inherently more complicated.
designing for those scenarios increase complexity; cost; architecture style and most of the time it will bring you in microservices territory where most of the companies lack experience and just are following best practices in a field where engineers are expensive and few