

Cloudonomics: High Availability should be a part of your cloud computing ROI - blackcat786
http://www.ringio.com/2010/07/08/cloudonomics-high-availability-should-be-a-part-of-your-cloud-computing-roi-calculation/

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stingraycharles
This article raises some fair points, but it comes off as a bit biased and
compares extremes a few times.

 __ _"Geographic Redundancy and Diversity

The Cloud Way: The cloud out of the box gives you the power to instantiate
your services in geographically diverse regions.

The Traditional Data Center: To do the same with your own data centers is very
costly / time consuming / resource intensive. "_ __

There are many ISP's that allow you to rent multiple servers spread across
multiple datacenters. As a matter of fact, we are with an ISP that has 5
geographically separated datacenters and renting dedicated servers there. It's
not that different from setting it up in the cloud, you run into the same hard
problems: replication, master/slave, latency, split brain problems, etc.

 __ _"Load Balancing & Basic Monitoring

The Cloud Way: The cloud provides this at a basic level and gets you off the
ground quickly.

The Traditional Data Center: You don’t need to implement your own solution
unless you really need to do some advanced loadbalancing for example."_ __

This is another thing that many regular hosting providers offer. Monitoring
and load balancing is not something that's unique to clouds.

All in all, while I agree that in some situations, a cloud offers you more
possibilities to easily achieve high availability, some of the hardest
problems remain unsolved. When you actually want very high availability and
consistency across multiple geographically separated locations, cloud or no
cloud, it's still going to be incredibly hard to solve.

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amphoraa
> When you actually want very high availability and consistency across
> multiple geographically separated locations, cloud or no cloud, it's still
> going to be incredibly hard to solve.

But then... you're talking about a niche. Granted, no consolation if you are
in it, but most people are not.

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hannah74
I find it ironic that we techies select the cloud mostly for technical reasons
when the economic argument is equally compelling if not more

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wmf
This is a pretty rosy view considering that AFAIK basic HA tasks like taking
over an IP address from a failed machine is much _slower_ in the cloud. And
let's hope your HA software doesn't want to use multicast...

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blackcat786
The need for HA software to remap ip's should not be there if the service has
been designed in a stateless manner. As soon as a service goes down the
balancer should send the next request to the next node.

In addition - At the entrance of the cloud(external ip's of the balancer) - I
would suggest dnsmadeasy that can do round robin dns along with dns monitoring
with a low ttl of 5 minutes that in case of failure can change your A records.

So the service should be designed with not having to rely on ip re-
assignments.

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aymarabob
What I would like to know is how many of those balloons can pop before the
whole "solution" stops being highly available for that cloudwalker ;-P

