Understanding Cloud Characteristics - Deploying and Managing a Cloud Infrastructure - page 13

Security
One of the primary reasons to go for single tenancy is security. Some regulations within
healthcare (HIPAA/HITECH) and finance (PCI-DSS) demand that personally identifiable
data or critical financial information be physically segregated to prove that it's properly
secured. This has been one of the stumbling blocks in the adoption of the cloud, especially
public cloud solutions within the healthcare and financial sectors. The remedy to this chal-
lenge is to encrypt all critical data before it leaves a controlled premises (company) and
heads to the cloud. In response to this challenge, the public cloud providers offer single-
tenant dedicated encryption key managers that run on instances with physical boundary
segregation from other tenants, ensuring that data security keys are housed in a physically
separate server.
Cloud Bursting
Typically, there are three different cloud deployment strategies: private cloud deployment,
public cloud deployment, and hybrid. Cloud bursting is used with the hybrid cloud deployment
strategy, where the deployment utilizes a mix of an in-house private cloud and a public cloud,
as the term hybrid suggests.
Cloud bursting is something that mainly enterprise cloud tenants would have to implement
because most of the consumer-facing web applications run completely on public clouds.
In enterprise cloud deployment, a typical use case would be catering to applications
that are workforce facing, like enterprise resource planning (ERP) and internal financial
and management applications. These applications would have a set of defined users and
predictable future resource requirements. Then there are applications for the enterprise
that are either consumer facing or the kind that can experience sudden spikes in use.
Because the private cloud deployment would entail a company's own data center with a
set number of physical servers, catering to these spikes in usage would mean adding more
physical resources into the data center. The other option would be to implement cloud
bursting, which would mean that whenever there's a spike in usage beyond the capacity of
the physical resources available within the company's private cloud, the additional users
would all be routed to the public cloud.
When you're implementing the cloud bursting strategy, you would need to consider
transparent switching, load balancing, and security.
Transparent Switching
Enterprise applications running on top of the private cloud usually do not implement the
automated switching required when the private cloud runs out of resources. This switching
happens between the virtualization and application layer. For example, Amazon Virtual
Private Cloud (Amazon VPC) allows for a private cloud to connect with compute/storage/
networking resources allocated inside Amazon's cloud through a VPN connection.
Another interesting company that sensed the need to deploy hybrid clouds and to
be able to transparently switch between them based on their performance or business