Monday, April 12, 2010

Pros and Cons of Blade Solutions for Virtual Infrastructure

In comparing blade vs traditional server solutions for virtual infrastrstructure (VI), there are pros and cons for both. Itemizing the advantages and disadvantages each solution will help an IT department justify and defend the decision to go one direction or the other. Of course Blades may be better suited for one customer and servers a better solution for another, there are many factors considered in making the ultimate decision. Below are a few of the more common aspects to consider when trying to decide on blades or servers.

Definitions:

Blade Server solutions:
In a blade chassis a set of blade servers will conventionally share power and cooling
http://en.wikipedia.org/wiki/Blade_server
More recently there is a new trend to also share networking and storage I/O through converged network adapters (eg Cisco's Unified Computing System (UCS))

Server solutions:
In contrast to the blade solution, each server is an autonomous with respect to its components - power, cooling etc - nothing is shared.

Pros and Cons:

Blade Solution:
Pros:
  • Efficiency: via shared power and cooling blade servers offer better efficiency in these areas
  • Density: blade servers offer higher density per rack U for CPU resources (although this can be a con if your datacenter can not handle the power and cooling density)

Cons:
  • Cost: Requires the additional expense of a chassis to house the blades
  • Lock-in: Chassis represents added level of vendor lockin due to the chassis investment (which may cost as much as $30,000 or several individual servers)
  • more lock-in: related to lock-in are the reduced negotiating power on pricing, and loss of business agility to go with best of breed as easily as when deploying standalone servers
  • All eggs in one basket (if the blade chassis has an issue or needs maintenance, all VMs hosted its blades will be down at once)
Standalone Server Solution:
Pros:
Cost: no chassis to pay for - can take advantage of the latest competitive pricing
Business Agility: allows choice of best of breed technology (without the lock-in of the blade chassis)

Cons:
Efficiency: takes more power and cooling per rack U than the shared blade chassis
Density: offers less rack U CPU resource density

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