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Comment by mkj | Hacker News Reader

Huh, so the "3 availability zones" are 3 datacentres on a 1km stretch of road? https://goo.gl/maps/CSpsvPWsxNE2

Why would that be surprising?

Seems they might share fibre susceptible to excavators, etc. I guess they've probably thought of that ;)

Availability zones are physically separate, but I wouldn't count on them to survive a catastrophic physical event localized to that geographic area.

AWS in contrast likes to spread things out more, like in Northern Virginia where they have 5 different AZs that are supplied from different electrical substations and confer some 'more than one block down the street' geographic separation. While a bunch of them are in the usual Ashburn-Sterling-Dulles triangle on north of Dulles Airport, there's also ones in Chantilly on the south side of the airport, and past Manassas another 15 miles out.

When AWS rolled out in Ohio, they did the same thing [1], locating two of them in the suburbs northwest of Columbus and one northeast, or in Sweden where they're in Västerås and Eskilstuna on opposite sides of a large lake, and a third in Katerineholm another 50 km out.

[1] https://news.ycombinator.com/item?id=12730012

I don't know where AWS is in Sydney, but I'd be surprised if they had a lot of options for doing better than this small stretch of Equinix area.

Aside from Equinix, the are the two Global Switch buildings literally next to each other, and there's NextDC.

In Sydney, Digital Reality opened a site in 2012 out in the western suburb of Erskine Park, almost 40 km from the CBD, but within 3 km of the Transgid Sydney West 330/132kV Substation, one of the key pieces of power supply infrastructure in the Sydney Metro. That facility has 4 separate bays where a tenant can operate a full data center [1].

NextDC is in Macquarie Park, ~10 km from the CBD, and is adjacent to one from Fujitsu and one from Macquarie Telecom.

Siting in these three areas, for example, would confer a decent amount of geographic separation.

[1] https://www.digitalrealty.com/data-centers/sydney/#goto-1718

AWS probably also uses Equinix facilities in many regions.

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