Tuesday, 2 December 2014

DataCenter 101 – Rack Fundamentals

You might have heard a lot about “Rack-stack” while planning a new deployment, but did you got chance to have a view of it. You might see them everyday, but did you noticed what’s its type or what is missing or what can make it better while planning its life cycle? In my last article I provided an Overview of DataCenter. Now, Lets walk through DataCenter Racks.

Racks and Enclosures are the building blocks of DataCenter, which manage the real estate space inside them, where all equipment are kept. There are two types of enclosure used in datacenter.

1.       The 19 Inch Standard – Its designed based on EIA-30 standard to ensure the physical compatibility between  racks and equipment mounted in those racks. The is the mostly commonly used rack world wild. Every rack has size units as “U”, where 1U=1.75 inches. Usually 42U is the standard rack size. Dimensions for these racks  are : 17.72 inches gap between side rails or called as Enclosure opening  to mount equipment; while the width between the mounting holes is nearly 18.31 inches; thus the overall minimum width for front panel is nearly 19.03 inches. These racks have Square Nut mounting Rails which come along with the equipment.

2.       The Earth quake Standard – International Building Code  and Euro-code specifies how these racks should be bolted to floor where there is a high risk for earth quakes ; while NEBS and ETSI mentions the rack alignments enforcement for these racks.

Based on type, racks can be further divided into two categories:

1.       Open Frame Rack – Two Post Frame or called as Rely racks holds equipment which can be mounted front or center. It is used mainly for lightweight low cost equipment like switches; however they offer No security, No airflow control, low weight capacity and low stability. Four Post Frames give support for both Back and Front mounted equipment, which makes them more versatile. These are used for servers, storage and network equipment. It is physically stronger and hence can support heavy equipment.

2.       Enclosures: These are advanced rack containment system with front and back doors, side panels and a roof. These advance racks provide forced air flow and hence enhanced air cooling capability. These are mostly used as Server Enclosures. In past years, they have been getting deeper to support dense equipment. Though usual size is 42U, but they can be as tall as 48U, however while deploying 48U racks you need consider overhead equipment like fire safety sprinklers or cable guidance. Network enclosures are usually 48U since they need wide space for cables and master switches, which can accommodate upto 2000 cables approx.
3.       Wall Mount Enclosures: Now there is a special category of enclosure, small in size, which conserves floor space and provide neat installations. I haven’t seen them in practical use though, still counts as a category.

Note: Non-standardized racks can lead to high costs since they may not accommodate the equipment designed for standard rack. It is always suggested to buy Vendor Neutral Standard racks, which comes with guarantee to support all vendor equipment.

Rack Accessories: Based on the requirements, many rack accessories can be deployed along with rack, which includes KVM monitors, Cable Management kits, PDUs, Cooling fans etc.

Floor Plan
While designing your Racks, you need to think about Availability. In-sufficient air flow or power can damage your equipment. Even if the cables are stretched, they can get damage or unplugged. Remember your floor plan and rack spacing is most important while designing your datacenter. It take cares of the HVAC (Heating Ventilation and Air Conditioning). (image found from google in one of the blog, using it to explain). However, make sure your don’t compromise on the physical security of the rack access. Cold asile should be 4 ft wide while hot should be 3 ft.
How to do Effective Air Flow in Racks:
  • Use blank panels to prevent heat exhaust from being recirculated. So Don’t through your blank panels, many people fail to realize their importance.
  • Use of Net doors in back and front panel, though they come with design now
  • Implementation of Air Distribution Units (ADU) which are commonly mounted at the bottom of the rack are designed by EIA-310 19 inch rack standard. These units pulls the cold air and supply them directly to the rack.
  • Implementation of Side Air distribution Units, which gets installed above the rack, provides side-to-side air flow.
  • One more scalable solution available is Air Removal Units, which just removes the hot air coming from the equipment.
PThats all I had to share about the Racks, I hope after reading this article you would be visiting your Server rooms, datacenter or labs to see what kind of equipment do you use. 

Any more questions? please write back or comment here. There are more things to share.. 

Request you to join my group on Facebook & LinkedIN with name "DataCenterPro" to get regular updates. I am also available on Tweeter as @_anubhavjain. Shortly I am going to launch my own YouTube channel for free training videos on different technologies as well. 

Happy Learning!!

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