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Blade Server Buying Guide

Blade Server is a traditional server architecture where multiple individual servers (blades) plug into a common chassis.

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PCQ Bureau
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Blade Server is a traditional server architecture where multiple individual

servers (blades) plug into a common chassis. Blade servers have a modular design

optimized to minimize the use of physical space. Many traditional server

components are removed and consolidated into the Blade Chassis or Enclosure to

save space and minimize power consumption amongst other considerations. Services

such as power, cooling, networking, various interconnects and management are

provided by the blade enclosure.

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Need For Blade Servers

Generally, all IT departments face a typical challenge of increasing number of

servers when different applications require separate infrastructure and

platforms. As a result a lot of space is required to house these servers and

that is where the problem of real estate management comes in as it leads to an

additional financial burden on the company. This is because when you are

expanding physically, you not only need the space but also need the standard

requirements of building a fresh server room/datacenter which consists of power,

cooling, management, etc.

You need a more powerful technology which offers the option of expansion, and is

less power hungry in the server space. Thus, broadly speaking, consolidation

around a lesser number of servers is where blade servers score.

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Blade Server Benefits

Reduced Space Requirements - Greater density and better use of the server

form factor highly reduces the total space requirements of the blade server

deployment as compared to tower or rack mounted servers.

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Reduced Power Consumption and Improved Power Management — Power

supplied from the blade server chassis highly reduces the total power supply

requirement and also reduces the power required per server.

Lower Management Cost - server consolidation and resource

centralization simplifies server deployment, management and administration and

improves management, redundancy and control.

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Simplified Cabling - Blade servers simplify cabling requirements and

facilitate highly reduced wiring. Most of the wiring related interconnects are

inbuilt into the chassis thereby greatly reducing the need for separate wiring.

Ease of upgrade - as new processor, communications, storage and

interconnect technology becomes available, it can be implemented in blades that

install into existing equipment, upgrading server operation at a minimum cost

and with no disruption of basic server functionality.

Easier Physical Deployment — since the chassis is responsible for

providing the once redundant parts of a server,deployment of a blade server

simply involves the placement of the chassis and sliding in the blades.

Redundant power modules and consolidated communication bays simplify integration

into data centers.

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Flexibility- Blade systems also provide significant configuration

flexibility, offering a choice among myriad servers, I/O options and other

internal components. The chassis can accommodate a mix of x86 (Intel or AMD

CPUs) and Unix RISC servers, storage blades, workstations and PC blades, as well

as multiple I/O connections per blade.

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General Blade Server Architecture

The hardware components of a blade server are the switch blade, chassis (with

fans, temperature sensors, etc), and multiple compute blades. The blades reside

in a standard compute blade slot,but they may functionally be positioned between

the switch blade and the compute blade. The switch card, present on the blade

server, is used to connect to the blade server. The switch card distributes

packets to blades within the blade server. A network management system software

is used to wrap around these components of the blade server. Other functionality

such as onboard graphics and VGA output, and USB connectivity etc are provided

on the blade but this only leads to lesser advantage taken of the blade server

architecture.

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Categories of Blade Servers

Blade servers can be divided into the following categories:

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Workstation Consolidators: Workstation consolidators are essentially

the tools to consolidate older RISC workstations into a neat,concise and

centrally managed server. Most of these solutions have single processors, slower

processor speeds (650 MHz) and limited memory capabilities (2 GB).they reduce

econic burden on the enterpise by reducing the datacenter space for the

enterprise,but offer little improvement in terms of operational expense

reduction.

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Repackaged Whiteboxes: Fundamentally the same x86 servers but in a

different form factor with limited processor and memory configurations. Some

differences between the traditional whiteboxes and repackaged whiteboxes are

that some common components (power supplies and fans) are removed from the

individual servers and placed in a common chassis. The blades themselves are

plugged into a common midplane to access these common components.The common

chassis may contain embedded network and storage switches. The applicability of

these products to smaller, less-mission-critical applications is limited.

Enterprise-class Blade Systems: Enterprise-class blade systems are

designed to interoperate in the modern datacenter with established network,

storage, security and management processes and category-leading tools.

Systems that contain embedded switches from different vendors may encounter

compatibility problems. An enterprise system should present a standard network

and storage card interface.

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It is crucial for the enterprise-class chassis to appear as a server (host)

to management framework tools. Again, an embedded switch may present differently

to the management and security framework, causing operational challenges.

Enterprise-class systems need to interoperate with leading SNMP-based datacenter

management tools.

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Blade chassis showing size of blades that have

been inserted.

Enterprise-class blade systems offer greater resiliency by reducing points of

failure and providing built-in failover, enabling greater application

availability and allowing the system to self-heal(redundancy) if a failure does

occur. An enterprise-class system must leverage internal network technology that

overcomes the latencies of standard Gigabit Ethernet. This allows applications

to respond more quickly and scale more widely.

Enterprise-class systems have anonymous server blades which contain no local

storage and, as a result, do not possess any specific, permanent identity.These

systems also provide greater horizontal application scalability. Because data is

managed outside the blade server, hardware can be brought into service, changed,

replaced or upgraded with limited manual intervention.Instead, the identity, or

state, of the server is hosted on external storage.

Features Of Blade Servers

The different blade manufacturers vary in specific configurations for their

blade servers and chassis, but the focus still remains to strip extraneous

components from the blades so the blades' components can focus on essential

processing and services. Each blade is a server by itself and generally

dedicated to a single computing task such as file sharing, SSL, data processing,

Web page serving, cache management ,video/audio streaming, or firewall etc.

Blade servers provide greater I/0 connectivity, hot swap drives, and RAID-5

capabilities.

Form factor

1 RU (one rack unit, 19" <48 cm> wide and 1.75" <4.45 cm> tall) defines the

minimum possible size of any equipment for a server architecture. So a typical

rack will be able to hold 80-100 servers with space in between for the cable

management units. For Blade servers, densities of 100 computers per rack,

running back to back, are commonplace. This also assists in the power management

and power conditioning where UPS units can accommodate more servers since,

because of the space and power-saving, they are more efficient. The principal

benefit and justification of blade computing relate to lifting this restriction

as to minimum size requirements. As of 2009, densities of up to 128 discrete

servers per rack are achievable with the current generation of blade systems.

Virtualization

In a single blade chassis, you can have different operating systems, different

memory capacities, a mix and match of 32-bit or 64-bit CPUs, and so on. Once you

have these, you can always run virtualization software on top. Also,blades let

you pair your dynamic software with dynamic hardware, making deployment and

management of virtual servers much easier.

Hot Swapping:

Hot swapping is the ability to add, remove and replace units at need without

having to power-off the chassis. Hot swapping can apply to PSUs, network,

management and storage units, and the blade servers themselves. Hot swapping,

coupled with redundancy, can give significant reliability benefits.It also aids

maintenance, because if a blade develops a problem it can be removed and

repaired or replaced without disruption of the other blades in the system.

Power:

The blade relies on the chassis to provide Power. In all chassis power switching

balances power load and requirements across the component blades' demands. The

technology ensures that power isn't wasted running underused blades, but in

times of high demand there is sufficient power available. Employing power supply

unit redundancy is necessary for critical servers.

Cooling

A full chassis may generate considerable heat from the activity of component

blades, so high demand blade servers require effective cooling from their

chassis to operate efficiently. The chassis' internal management systems may

shut down the entire system if the temperature rises above a certain point. It's

critical, then, to follow the directions of the blade server chassis'

manufacturer when managing the server's cooling. This might include air space

around the chassis, the use of plugs for empty bays, and environmental demands

for air temperature and humidity. Connectivity At the heart of the chassis'

connectivity will be an Ethernet and/or Fibre Channel switch, connecting each of

the blade servers to the LAN (Local Area Network). There may be more than one

switch unit in a chassis, which can either be used to provide a redundant

connection to a single network, or connection to more than one network. Other

connectivity is also provided by the chassis, but this is typically limited to

USB and VGA for monitor connection, with possibly PS2 connections for I/O with

mouse and keyboard. It's also likely that a chassis will contain an optical

drive, although at need all of these functions and more can be added to the

chassis through the use of specific blades in the system.

Storage

There may be some limited storage on a blade server, and there may be additional

storage provided by a chassis. However, with the use of a SAN ,the chassis and

blades can be completely free of storage, removing the inherent heat, noise, and

reliability problems from the system completely. Everything from booting to data

storage can be done over the SAN, enabling the blade servers to be focused

entirely on processing. This configuration can increase reliability and reduce

space requirements by partitioning storage resources in one centralized location

and computing resources in another. This also eliminates storage Despite the

advantages of storage outside the blade chassis, many blades have the capacity

to take one or two hard drives, usually SATA.

LED Indicators:

Blade servers typically have a front panel containing a number of informational

LEDs, relating to power and system activity. There may additionally be

indicators of system failure, which may be general or specific to blade

components. These optional features will invariably come at a cost premium.

Services and warranty:

Check out the services and warranty provided by the vendor. Are they providing

door services or you need to send the server to them to fix it. The door service

is obviously good. Moreover check out the warranty period they offer, mostly the

3-year warranty period is provided. In addition to this, many vendors provide

enhanced warranty with faster response time. This will cost you some extra penny

but it is worth if you are running mission critical application on it.

However, not all factors are relevant to every organization. The more

customized the blade servers are,the easier it is for the enterprise to take

full advantage of them. It is critical to match the blades you buy with your

application scenario. It could mean the difference between costly confusion or

intelligent integration of blade servers in your enterprise.

Shikhar Mohan Gupta

buying-guide server
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