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"Of course you're right, multiple AZs can fail at the same time, but I read the above as saying that they should fail independently/coincidentally." As far as
by jeresig 16y ago
"Of course you're right, multiple AZs can fail at the same time, but I read the above as saying that they should fail independently/coincidentally."
As far as I know we've heard nothing to the contrary from Amazon - it's totally possible that multiple AZs happened to fail independently/coincidentally. Perhaps it was simultaneous equipment failure? Or maybe one AZ failed and a sufficient number of people attempted to "fail over" to another AZ causing a chain reaction of failure?
- justinsb 16y agoIt is possible. I think it's exceptionally unlikely. The one bit of information we have suggests that the root cause was a networking issue, which suggests SPOF.
- leoc 16y agoIf I had to, I'd guess that AWS's messaging/monitoring/control infrastructure is likely to be the SPOF, as in the 2008 outage: http://status.aws.amazon.com/s3-20080720.html http://status.aws.amazon.com/s3-20080720.html It's an obvious weak spot in the independence/isolation of AWS' nodes, and it would seem to be the one most likely to cause failure to reach across more than one AZ. (Apart from a stampede from one, affected AZ to others perhaps.)