What is Cloud?
A cloud consists of three components, one or
multiple datacenters, a network and a “zillion” number of devices.
That’s what it’s all about, the components and their interaction.
Ultimately the user is interested in the end-to-end experience,
regardless of the components.
A cloud is grouped into private or public cloud based on the location
of the data center where the services are being virtualized. In
general, a public cloud is an environment that exists outside the
purview of company firewall, could be a service/technology offered by a
third party vendor while private cloud acts behind the firewall for the
exclusive benefit of an organization and its customers.
Source : HP
Testing and the Cloud
While many companies are approaching cloud
computing with cautious optimism, testing appears to be one area where
they are willing to be more adventurous. There are several factors that
account for this openness toward testing in the cloud:
•
Testing is a periodic activity and requires new environments to be set up for each project
Test
labs in companies typically sit idle for longer periods, consuming
capital, power and space. Approximately 50% to 70% of the technology
infrastructure earmarked for testing is underutilized, according to both
anecdotal and published reports.
•
Testing is considered an important but non-business-critical activity. Moving
testing to the cloud is seen as a safe bet because it doesn’t include
sensitive corporate data and has minimal impact on the organization’s
business-as-usual activities.
•
Applications are increasingly becoming dynamic, complex,
distributed and component- based, creating a multiplicity of new
challenges for testing teams.
For instance,mobile and Web
applications must be tested for multiple operating systems and
updates,multiple browser platforms and versions, different types of
hardware and a large number of concurrent users to understand their
performance in real-time. The conventional approach of manually creating
in-house testing environments that fully mirror these complexities and
multiplicities consumes huge capital and resources.
Why Opting for Cloud Computing as source of Performance testing
Many companies use their Web sites for sales and marketing purposes.
In fact, a company can spend millions of pounds creating engaging
content and running promotional campaigns to draw users to its site.
Unfortunately, if the site crashes or response time crawls all that
time, energy and money could be wasted.
A first case is when demand for a service varies with time.
Provisioning a data center for the peak load it must sustain a few days
per month leads to underutilization at other times, for example.
Instead, Cloud Computing lets an organization pay by the hour for
computing resources, potentially leading to cost savings even if the
hourly rate to rent a machine from a cloud provider is higher than the
rate to own one. A second case is when demand is unknown in advance.
For
example, a web startup will need to support a spike in demand when it
becomes popular, followed potentially by a reduction once some of the
visitors turn away. Finally, organizations that perform batch analytics
can use the ”cost associativity” of cloud computing to finish
computations faster: using 1000 EC2 machines for 1 hour costs the same
as using 1 machine for 1000 hours. For the first case of a web business
with varying demand over time and revenue proportional to user hours, we
have captured the tradeoff in the equation below.The left-hand side
multiplies the net revenue per user-hour by the number of user-hours,
giving the expected profit from using Cloud Computing. The right-hand
side performs the same calculation for a fixed-capacity datacenter by
factoring in the average utilization, including nonpeak workloads, of
the datacenter. Whichever side is greater represents the opportunity for
higher profit.
Cloud Areas and their Differentiators:
- Private cloud
is on premise, dedicated to one organization, often located in the
same datacenter(s) as the legacy applications; address the needs
of mission critical applications and applications having access to
large amount of confidential data.
- Hosted private cloud
is really a variant of the previous category, located either in
the client’s or the hoster datacenter, but managed by a hosting
provider. It addresses the same needs as the private cloud.
- Virtual private cloud
is a single or multi-tenant environment, located in a clearly
defined geography, with documented and auditable security processes
& procedures, clear SLA’s, addressing the needs of business
critical applications. Formal contracts are established, payment is
by consumption, but with regular invoices. Access to the
environment can be over the internet, VPN or leased lines. HP calls
this an Enterprise Class Cloud.
- Public Cloud
is a multi-tenant environment providing IaaS, PaaS and/or SaaS
services on a pay- per-use basis without formal contracts. Payment
is typically via credit card. Such environments address the needs
of web applications, test & development, large scale processing, (if
not too much data needs to be transferred).
Source: HP
The first two categories are asset intensive and typically do not
lend themselves to a pay-per-use model; the latter two are pay-per-use.
The first two are typically single tenant, this means they are used by
one organization; the latter two are most often multi-tenant
environments where multiple companies share the same assets.
Performance Testing in Cloud – Benefits & Limitations:
• Fast provisioning using preconfigured images
. You can set up the infrastructure you need in minutes.
• Simplified security. All required protections are set up by default, including firewall, certificates, and encryption.
• Improved scalability. Leading
load testing solution providers have negotiated with cloud providers to
allow users of their software to employ more virtual machines (for the
purpose of load testing) than are allowed by default.
• A unified interface for multiple cloud providers.
Load testing solutions can hide provisioning and billing details, so
you can take maximum advantage of the cloud in a minimum of time.
• Advanced test launching. You can save time and effort by defining and launching load generators in the cloud directly from the load testing interface.
• Advanced results reporting. Distinct results from each geographic region involved in the test are available for analysis.
Limitations:
Although testing from the cloud is, in many cases, more realistic
than testing in the lab, simply moving to the cloud is not enough to
ensure the most realistic tests. Real users often have access to less
bandwidth than a load generator in a cloud data center. With a slower
connection, the real user will have to wait longer than the load
generator to download all the data needed for a web page or application.
This has two major implications:
• Response times measured as-is from the cloud with virtually
unlimited bandwidth are better than for real users. This can lead test
engineers to draw the wrong conclusions, thinking that users will see an
acceptable response time when in reality they will not.
• The total number of connections established with the server will
increase, because on average, connections for real users will be open
longer than connections for the load generator. This can lead to a
situation in which the server unexpectedly refuses additional
connections under load.
Conclusion: The
benefits of Cloud Computing Solution cannot be ignored by companies
running Performance tests striving to overcome the constraints of their
current IT hardware to simulate the realistic environment whilst
struggling to justify the cost of investing in major upgrades.
