Hardware Reference
In-Depth Information
software developed for WSC. One advantage would be easy support of “hybrid” datacenters,
where the workload could easily be shipped to the cloud in a crunch and then shrink back af-
terwards to relying only on local computing.
Among the many atractive features of cloud computing is that it ofers economic incentives
for conservation. Whereas it is hard to convince cloud computing
providers
to turn of unused
equipment to save energy given the cost of the infrastructure investment, it is easy to convince
cloud computing
users
to give up idle instances since they are paying for them whether for
not they are doing anything useful. Similarly, charging by use encourages programmers to
use computation, communication, and storage efficiently, which can be difficult to encourage
without an understandable pricing scheme. The explicit pricing also makes it possible for re-
searchers to evaluate innovations in cost-performance instead of just performance, since costs
are now easily measured and believable. Finally, cloud computing means that researchers can
evaluate their ideas at the scale of thousands of computers, which in the past only large com-
panies could aford.
We believe that WSCs are changing the goals and principles of server design, just as the
needs of mobile clients are changing the goals and principles of microprocessor design. Both
are revolutionizing the software industry, as well. Performance per dollar and performance
per joule drive both mobile client hardware and the WSC hardware, and parallelism is the key
to delivering on those sets of goals.
Architects will play a vital role in both halves of this exciting future world. We look forward
to seeing—and to using—what will come.
6.10 Historical Perspectives and References
Section L.8 (available online) covers the development of clusters that were the foundation
of WSC and of utility computing. (Readers interested in learning more should start with
Barroso and Hölzle [2009]
and the blog postings and talks of James Hamilton at
ht-
Case Studies and Exercises by Parthasarathy
Ranganathan
Case Study 1: Total Cost Of Ownership Influencing
Warehouse-Scale Computer Design Decisions
Concepts illustrated by this case study
■ Total Cost of Ownership (TCO)
■ Influence of Server Cost and Power on the Entire WSC
■ Benefits and Drawbacks of Low-Power Servers
Total cost of ownership is an important metric for measuring the effectiveness of a
warehouse-scale computer (WSC). TCO includes both the CAPEX and OPEX described in
Sec-
tion 6.4
and reflects the ownership cost of the entire datacenter to achieve a certain level of
performance. In considering different servers, networks, and storage architectures, TCO is of-
ten the important comparison metric used by datacenter owners to decide which options are
best; however, TCO is a multidimensional computation that takes into account many different
factors. The goal of this case study is to take a detailed look into WSCs, how different archi-
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