Blade Servers refer to Chassis based Server modules. We will look at the various components that go in to the Chassis of Blade Servers as well as the advantages of Blade Servers (over rack mount servers) for large server deployments, in this article.
First, what is a Chassis?
Chassis refers to any backplane module that has empty slots where the front end modules (like blade servers) & add-on modules can be inserted. All the individual modules/ components can be inserted in to the empty chassis slots (or) somewhere in the chassis as add-on modules. The chassis comes with a certain fixed number of slots, and with many vendors, the chassis as a whole can be fixed in to a standard 19″ server rack. The major components of the Blade Server Chassis are listed below:
- Server modules (Blades) with Multi-Core Processors, RAM, hard disks, etc. These blades are inserted in to the empty front end slots of the Chassis.
- Common Power Supply Modules.
- Common Fan/Cooling Modules.
- Midspan connections (usually specialized cables) that connect specific add-on/integrated Chassis modules and Blade modules.
- Common Input/Output expansion modules (Eg. PCI Express modules).
- Specialized expansion modules (Like RAID expansion modules, etc).
- Storage Module(s).
- Networking Module(s) (Switch ports, Ethernet cables, etc).
Advantages of Blade Servers (Over Individual Rack Mount Servers):
Redundancy:
This is one of the most important advantages of Chassis based Blade Servers. Blade Servers introduce redundancy with many components – The chassis contain (n+1) power supply modules (common to all the blades) which provide redundancy in case of individual power supply module failures. This is better than providing (n+1) power supply modules within each server. These modules can be powered from different grids/ different phases to provide additional power resiliency. The fan modules (used for cooling) too have an n+1 configuration for redundancy. Even the individual connections from the blade servers to the chassis backplane which provide common I/O, switch ports etc, can be made redundant by providing additional connections that run in parallel.
Consolidation:
Since Blade servers are generally used for larger server installations, a number of components can be consolidated for the entire chassis instead of being provisioned (usually in excess) for each blade. For example, the I/O modules (Eg. PCI express modules) can be consolidated over the chassis and any of the blade servers can utilize them as and when required. This is better than provisioning multiple I/O modules in every server. With consolidated provisioning, lesser modules are required, hence reducing the overall cost. Even the power supply and cooling modules are consolidated over the entire blade (in the chassis) and is better than having individual power modules/ cooling modules for every server, as lesser modules are used in the chassis.
Centralized Management:
Most of the components in blade servers can be centrally managed using a unified management application, and some vendors allow for remote management/ administration too. So, along with the blade servers, the storage modules, networking modules, I/O modules, power modules, cooling modules etc, can be administered as a single system. Sometimes, even multiple such Chassis (from a single vendor) can be managed from a single system. This makes the administration of blade servers easier.
Easy Servicing/ Replacement:
Chassis based blade servers generally offer easily removable, and in most cases hot pluggable individual modules. For example, if one of the fan/ cooling modules are not working, they can be removed and replaced without having to switch off the entire chassis. This provides for easy and uninterrupted replacement of individual chassis modules.
More Processing Power:
Blade Servers can accommodate more processing power, per rack unit within each server module. This is possible as the cooling and power supply modules are removed from the individual blade servers and consolidated on the chassis. This extra space can be used to accommodate more/ higher capacity processors. As you can imagine, this creates more heat inside the server modules, and vendors offer additional fan modules/ liquid cooling systems to offset the higher levels of generated heat.
Bulk Deployment/ Scaling of Servers:
Blade servers with chassis are useful for bulk deployments and offer a way to quickly scale-up the number of servers. When all the slots of the chassis are filled up with blade modules, and a number of such chassis based blade servers are deployed, the resulting configuration has higher degree of efficiency, reliability, ease of management & ease of maintenance when compared to large number of individual rack server deployments. If additional servers need to be added, they can just be inserted in to the empty slots in the chassis/ add additional chassis modules and the whole system can be brought up and running, quickly.
Preloaded Operating Systems/ Server Virtualization Software:
Certain blade server manufacturers offer their server modules with preloaded operating systems as well as Server Virtualization softwares. This brings down the deployment time drastically and also gives a tighter hardware-software integration. With some vendors, even the individual processors/ threads can be dedicated to certain virtual systems and they can be enabled/disabled individually.
Wide range of deployment:
Blade Servers can be deployed for small as well as large deployments. Chassis based blade servers can be deployed to hold just a few servers ( For example, 6 blade server modules), (or) clusters of hundreds of interconnected blade server chassis can be formed. There are blade servers that just occupy half the width of a regular rack mount server and hence two such blade servers can be accommodated within a 1U slot. But these servers may come with reduced processing/ other capabilities, depending on the vendor.
Integrated Storage Modules:
Some vendors offering Blade Servers simplify the deployment of storage systems by offering separate storage modules that can be inserted in to the same slots of the chassis (like the blade server modules). This enables integrated server/ storage management. Some blade server vendors offer SSD (Solid State Devices) to store data with higher reliability and implement RAID based hard disk storage within each server modules, out of the box.
Integrated Network Switch Modules:
Some blade server vendors offer integrated network switch ports within the chassis either as add-on modules (or) as separate full fledged switching modules. All the server modules within the chassis can be connected to the switching module present in the chassis itself and multiple chassis can also be interconnected using these network switch modules. Since the chassis itself comes with the Ethernet ports, the total number of ports required for their interconnection with separate external Ethernet switches/ Network cables are reduced to a good extant.
Specialized Functions:
Certain blade server manufacturers offer specialized functions like remote KVM modules (for operating the server’s keyboard/mouse/monitor from a remote location), remote power-on/ power-off functions and various other functionalities that make deployment and management of these chassis based blade servers easier.
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