To blade or not to blade, that is the question! Well, at least it’s a question. The idea behind blade computing is a good one. Strip out and share key components such as power, cooling, storage and the like across multiple servers, reduce costs and simplify, simplify, simplify your IT infrastructure.
If every application workload fit well into a blade environment we wouldn’t need any other computing approach; unfortunately that’s not the case. Blade computing works great in some situations but can actually increase costs in others. The allure of blade computing is compelling, and aggressive marketing pushes by blade vendors can make blades sound like the logical solution, and often they are. In general, however, buyers must become more aware of the benefits and drawbacks of blade computing and fully understand the marginal costs and marginal benefits of this emerging approach. This is especially true in many smaller environments where companies don’t have the critical mass of blade-friendly applications to exploit the economics of blade servers. Often, the marginal costs of the chassis and the drawbacks of sole-sourcing outweigh the incremental benefits.
So, where do blades make the most sense and where do they not fit? And how should you best approach blade computing when the economics are compelling? Let’s look at:
- What is blade computing?
- Where does it fit?
- What economic value can blades bring?
- What are some of the key best practices that will translate into success?
- What does the future hold?
Contents |
What is blade computing?
Blade computing is an approach that combines blade servers, with enclosures that house these servers. Blade servers are very compact, high density servers that have their own unique cpu and memory but reduce the number of components on each server by sharing power, cooling, cables, networking, storage and consoles with other servers that reside in an enclosure or chassis. This approach squeezes more costs out of distributed computing by spreading the cost of these components across other servers in an enclosure, dramatically reducing the number of parts on each server. The most important thing about blade technology is it drives simplicity and commonality into IT infrastructures making them easier to manage, more space and power efficient and more resilient if designed properly.
Where does blade computing make the most sense?
Blade servers are perfect for applications like Web, email and certain analytics applications, and especially those workloads that are parallelizable, you know, those that can be easily spread across many different servers. But more complex workloads with higher transaction and update activity are often not well-suited for blade architectures. As each vendor attempts to position its respective blade products not only as superior to other vendor products, but also positioning blade computing as superior to other types of computing, some big promises are being made regarding the degree to which complex hardware configuration and operations work will disappear as a consequence of deploying blade computing.
The reality is, that for applications at the margin, such as very large transaction processing workloads or other large applications, especially those with high write to read ratios, making applications work on specially configured hardware that cannot be as standardized as blades can be, will remain a complex and challenging undertaking. However, for a broad array of applications such as Web serving, small applications/databases, file oriented and other unstructured workloads, blades can be an excellent fit, with some caveats that we’ll talk about when we discuss best practice considerations.
What economic value can blades bring?
It’s useful to look at the economic benefits of infrastructure in two dimensions:
- What hard dollar savings can be realized from blade computing?
- What incremental business benefits (so-called ‘soft dollars’) can blade computing bring?
While it’s always important to assess hard cost savings, our experience is that the real benefits with blade computing are seen in terms of better application availability and much faster deployment of change, specifically related to the provisioning of new server capacity.
Let’s take a look at some of these benefits and as well, the implications for blade computing marginal costs:
Hard dollar savings
The degree of cost savings or reduction in total cost of ownership will vary as a function of three factors:
- Critical mass of workloads that are candidates for blade computing
- Best practices used to exploit emerging hardware and software technologies
- Current levels of server consolidation
Workload critical mass is, well, critical. Many small businesses simply don’t have enough ‘bladeable’ applications and therefore are not good candidates for blade computing. These shops often are better served by staying with traditional server technology and shopping around for the best deal as their requirements dictate. Best practice in blade computing drives commonality into the server infrastructure (e.g. same server speed, same memory, same networking standards, same external storage, and same vendor) and this approach isn’t always the best for all businesses.
The degree of server consolidation is also important. If servers today are highly underutilized, distributed physically and not being professionally managed by IT people then greater savings will be realized with blade computing than if servers are already physically collocated in a datacenter. In most businesses, this physical movement into a centralized location has already taken place, but not always. The poorer you run server operations today, the more you’ll get out of blade computing or any consolidation for that matter.
Here are two representative examples that can help quantify the hard dollar benefits of blade computing:
Case 1: A medium-sized services company targeting blade computing at 1,200 Web services users, predominantly served with traditional collocated servers.
The Environment
- 30 Servers.
- 3TB’s of disk storage.
- Server growth of 25% per year.
Savings:
- ~5% on capital costs and environmentals.
- ~1/2 FTE.
- ~$350,000 over five years.
These savings are not huge but as we’ll see in a moment, cost savings is not always the predominant driver with blade computing.
Case 2: A large telco providing file and Web services to more than 15,000 users, predominantly served with traditional rack mounted servers.
The Environment
- 200 Servers.
- 20TB’s of disk storage.
- Server growth of 15% per year.
Savings:
- ~10% on capital costs and environmentals.
- ~3 FTE’s.
- ~$1.3M saved over five years.
In both case studies, the capital cost and environmentals savings were marginal and barely offset the incremental cost of enclosures. Improved productivity of IT staff was meaningful but not nearly as large as we’ve seen in many traditional consolidation projects.
Here is the conundrum of blade computing. Typically, the applications that can benefit the most from a blade approach are not those complex applications that are extremely labor intensive as is often seen in traditional server consolidations. The ones that are blade-friendly unfortunately are not going to allow you to take huge costs out of your infrastructure. But, every little bit helps.
Business side benefits
It’s the non-IT benefits or the so-called ‘soft dollars’ where case examples suggest the greatest benefits of blade computing come into play. Specifically, the advantages of creating a common server infrastructure that can be virtualized and supported with shared, centralized storage can be enormous. Consider the following case:
Case 3: An Internet services company with very high growth serving several million subscribers. The company was having a problem-- service levels for subscribers was poor and it was constricting the company’s growth. It was determined that the major problem with service levels related to commodity computing, namely OS failures and the inability to quickly fail back to previous versions of software. Disk failure and complex operating procedures were also culprits. The solution involved replacing rack mounted and standalone servers that used internal storage with a virtualized blade computing infrastructure and a consolidated NAS and SAN.
The Environment
- 200 Servers.
- 50TB’s of disk storage.
- Server growth of 15% per year.
- Storage growth at 50%+ per year.
Business Benefits:
- Application availability improved from 97% to 99.8%.
- Reduction in time to provision new servers and consequently new subscriber services went from days to minutes.
- The company experienced major improvements of system stability during the installation of new OSes and software releases.
- Completely eliminated IT infrastructure as an inhibitor to business growth.
- The company estimated this change was worth tens of millions of dollars in terms of improved customer satisfaction, revenue and employee productivity realized inside of twelve months time.
The point of these three cases is that while there are some cost savings to be realized with blade computing, the real business case stems from benefits related to simplifying change management and addressing fundamental IT challenges associated with managing commodity OSes and components.
Best practices
At a recent Wikibon.org research meeting comprised of experts, consultants and practitioners, a clear point emerged: Blade computing works best when organizations apply a ‘one-size-fits-all’ strategy, meaning all the blades in the chassis are as similar as possible and ideally, identical. This means same cpu, same speed, same memory, same everything, including the same vendor. By standardizing on blade servers, operating procedures can assume that every component in the chassis is identical and IT operations doesn’t have to worry about the sensitivity of a particular server component to an application’s unique characteristics. This makes blades more swappable, easier to manage, simpler to back up and cheaper to acquire and inventory. Greater diversity within the chassis defeats many of the benefits of blade computing.
If for whatever reason, you don’t want to enforce this degree of commonality, it is advisable that customers take an N and N-1 approach to blade server technology, meaning standardize on a couple of blade server types, one current technology and one current minus one generation, replacing existing server technologies every few years to keep the infrastructure simple. The business benefits of commonality, as seen in the case examples will outweigh any incremental hardware costs borne by this approach.
The other best practice worth noting from the Wikibon research meeting calls for using virtualization to separate storage from processors and ensure there is no fixed association of an application with a physical server. By using virtualization engines on the market today, system software can be centralized and version control can be managed. This means OS failures can recover from a central repository of OS versions enabling super-fast OS problem resolution by, for example, reverting to a previous version of an OS. By virtualizing the storage, data can be striped across multiple arrays so that no single disk failure will cause applications to crash. By separating storage from server, all recovery files such as journals which preserve the state of an application can be accessed by other servers, which minimizes the time to recover. Action item: Configure blades with storage external to the servers and ensure the servers have no fixed association with applications. Focus blade virtualization projects on creating simple robust environments that can withstand the failure of commodity components, and don’t worry so much about saving processor cycles.
The Future of Blades
Most server architectures today, including blades, generally assume a one-to-one correspondence between an application and a server. Web service delivery, however is driving demand for new blade server architectures and suppliers are beginning to re-think traditional definitions of servers. Blade computing can be an underpinning of new approaches to architecting network-based systems where the presumption of frequent component failure and highly distributed computing resources are fundamental to designs. By using inexpensive servers and assuming components will fail, the industry is being led to an architecture that spreads operating systems, file systems, applications and data across entire server infrastructures worldwide ensuring lightning fast response times and always-on application availability. While, for the most part, architectures being deployed today presume that one-to-one relationship between server and application, Web services and potentially blade computing are paving the way for new growth opportunities by spreading everything, everywhere and making worldwide grid computing a reality. If this sounds outlandish, one doesn’t have to look far to see how various Web services today are being delivered and you’ll reach this same conclusion—it’s happening right under our noses.
Action Item:
Footnotes: