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I wonder if its cheaper (and/or better) for a hosting provider to spend less on reliability and instead build in multiple redundancy. Thoughts? Also, i've neve

I wonder if its cheaper (and/or better) for a hosting provider to spend less on reliability and instead build in multiple redundancy. Thoughts? Also, i've never heard the expression 4 nines before, anyone explain that for me?

Hovertruck 15y ago
I assume it refers to uptime, e.g. 99.99% uptime.
tangothedog 15y ago
It's a common way to describe uptime. It means 99.99% uptime/availability, which works out to under 1 hour of downtime per year. http://en.wikipedia.org/wiki/Nines_(engineering) http://en.wikipedia.org/wiki/Nines_(engineering)
mdda 15y ago
4-nines is 99.99% reliability (downtime of about 1 hour per year). More detail :http://en.wikipedia.org/wiki/High_availability http://en.wikipedia.org/wiki/High_availability
esrauch 15y ago
The number of nines refers to how reliable something is. "Four nines" means that it is up 99.99% of the time, or 0.01% of downtime, which is 0.0001 * 365 * 24 = just shy of 1 hour of downtime per year (or 1 day downtime every 30 years). These things are usually specified in SLA (service level agreements) where if the provider exceeds the amount of downtime in the SLA means that you don't have to pay. If Amazon has a 4-nines SLA that means that you don't get any discount if they have 1 hour down per year.
pavel_lishin 15y ago
> I wonder if its cheaper (and/or better) for a hosting provider to spend less on reliability and instead build in multiple redundancy. Thoughts? Wouldn't it look the same from my end?
synnik 15y ago
Multiple Redundancy IS reliability. As long as everything stays running from the customer/business perspective, you are reliable. When you start to define reliability as a specific layer of your infrastructure, you are setting yourself up for problems. You should be redundant at all layers, thereby reliable across your entire stack.
deleted 15y ago
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Hovertruck 15y ago

I assume it refers to uptime, e.g. 99.99% uptime.

tangothedog 15y ago

It's a common way to describe uptime. It means 99.99% uptime/availability, which works out to under 1 hour of downtime per year. http://en.wikipedia.org/wiki/Nines_(engineering) http://en.wikipedia.org/wiki/Nines_(engineering)

mdda 15y ago

4-nines is 99.99% reliability (downtime of about 1 hour per year). More detail :http://en.wikipedia.org/wiki/High_availability http://en.wikipedia.org/wiki/High_availability

esrauch 15y ago

The number of nines refers to how reliable something is. "Four nines" means that it is up 99.99% of the time, or 0.01% of downtime, which is 0.0001 * 365 * 24 = just shy of 1 hour of downtime per year (or 1 day downtime every 30 years). These things are usually specified in SLA (service level agreements) where if the provider exceeds the amount of downtime in the SLA means that you don't have to pay. If Amazon has a 4-nines SLA that means that you don't get any discount if they have 1 hour down per year.

pavel_lishin 15y ago

> I wonder if its cheaper (and/or better) for a hosting provider to spend less on reliability and instead build in multiple redundancy. Thoughts? Wouldn't it look the same from my end?

synnik 15y ago

Multiple Redundancy IS reliability. As long as everything stays running from the customer/business perspective, you are reliable. When you start to define reliability as a specific layer of your infrastructure, you are setting yourself up for problems. You should be redundant at all layers, thereby reliable across your entire stack.

deleted 15y ago

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