Original subtitles

Various standards are available

detailing the requirements of the construction ot the equipment racks

that are commonly used in a data center

Most data centers use the traditional nineteen inch racks

the outer width ot these racks matches the size of the raised access floor tile

bei s centimeters or two feet

F or data centers with the raised access floor, this is a very common solution

Most data centers use racks are 4211 in

but some data centers do deploy taller racks being 4811 or beyond

the logic behind this the higher the rack

the more equipment that can be placed into these racks

But there are a few important considerations

F irst of all, can you reach the top of the rack safely while installing equipment ^

It is not advisable to have individuals standing on a flimsy box or ladder

trying to install equipment at the top of the rack, since that is a safety risk

Secondly far data centers which deploy cooling by using the raised floor

you need to ensure that the air which comes out ot the raised floor

can reach the top of the rack

This means that tor higher racks you need more pressure under the raised floor

which in turn means that the cod air that comes out of the raised floor

needs to be at a higher velocity

This could result in the equipment at the bottom

part of the rack being

part of the rack being partially bypassed

and therefore, leading to potential cooling issues

The unit RU or U is defined as 44 55 mm, or 1 Z5 inch

So again, 19 inch racks have an outside dimension

of approximately 60 cm or 2 ft in width

which allows these racks to be aligned with the raised access floor tiles

which are of similar dimension

In terms of the depth of the rack there's a large variety of depths to choose from

and in order to select the correct one

you have to review the physical dimension of the ICT equipment

and then choose a rack to match

Obviously, deeper racks will ensure that all types ot equipment will fit in nicely

However, the deeper the rack, lower the number of racks

that you can place inside the computer room

It is possible to use different rack sizes

within the computer room looking at both the height and the depth of the rack

But commonly data centers tend to use one type of rack

at least in one rack row

So. data centers are deploying twenty tour inch racks

These racks do normally contain the standard nineteen inch equipment

but they are wider to allow tor more cabling to be organised within the rack

Wider racks, similar as deeper racks

will reduce the number of racks that you can place in the computer room

Another potential drawback is.

that when your're using the traditional raised floor tiles

it will result in a misalignment as can be seen on this particular slide

The rack row on the left hand side is matching the floor tiles

whereas the rack row on the right hand side no longer has the one to one ratio

This may result in a small inconvenience

in the case of the racks having a different heat load

This normally results in using different floor tiles,

by looking at the perforation of the tile

in order to match the corresponding heat load in the rack

In other words, if there is more perforation in the tile

it allows for a higher volume of cold air to be pushed in the front of the rack

More information on these tiles will follow in the CDCS course

Rack types are categorized in two post and tour post racks

Two post racks are similar to dual frames

and should only be used for patch panel type of applications

and only in fully secured environments since anything in the rack is exposed

Note also that these racks heed to be botled to the floor

which may be a challenge in some data centre environments

Four post racks are perfectly suited for ICT equipment

They come with a variety ot door types at both the front and back of the rack

The type that you wish to use in your data center

depends on the security and cooling requirements

which will be discussed on the following slides.

One option is the glass door type of rack which can be seen on this slide

from a security point of view a decent rack

since nobody can touch the equipment or stick a sharp object through the door

The main concern, however with this type ot rack is cooling

When using a traditional

When using a traditional raised floor set up

and having a perforated tile in front of the rack.

the cold air cannot enter the rack due to the glass door being present

The only way to get cold air into the rack

is by having an opening undermeath the rack

Doing so you have to make sure that the opening under the rack.

where the cold air enters is directed to the front part of the rack

since that is the location where the cold air needs to enter the equipment

The hot air from the ICT equipment is leaving the rack somewhat via back door

which commonly has some ventilation outlets

Most of the heat load is extacterd via the fan assembly

which is at the top of the rack

The air volume extraction capability of this fan assembly

will ultimately determine the maximum heat load that you can place in the rack

which is often limited to a few kilowatts per rack only

Also, the older type of glass door racks

may not have a fan assembly built in but it can be retrofitted

Another minor concern the door being mainly glass

it is more prone to accidental damage

Perforated or grated dual racks have surface opening of typically ?0 45%

this will allow for a good amount of air flow to go through the door of the racks

and therefore, entering the ICT equipment allowing for good cooling capacity

These types of racks can hold up to

five kilowatt of heat load

Obviously the door needs to be unobstructed

and therefore, no stickers

and therefore, no stickers or papers should be present

It is not unusual to see computer rooms where there are papers in a folder

hanging on a paper clip on the inside of the door

and this will obviously hinder the air flow

Some perforated doors have quite big openings

which some organizations consider to be posing a higher level of risk

whereby someone could potentially stick a sharp object through the door

Whether this is really a risk depends on

the overall security management of the room

in which the racks are being placed

In an enterprise data center the risk is relatively low.

since only a handful of authorized staff members are allowed in the computer room

However, in a commercial data center in a shared computer room

the risk could be higher having potentially a lot of movement

depending on the number of customers, contractors

staff that are having access to that particular room

Mesh door racks have a large surface opening of up to eighty five percent

This will allow for a large amount of air flow to pass through the rack

and therefore providing an excellent cooling capacity

Configurations of up to fifteen kilowatts can be deployed in this type of rack

Although it has a large surface opening

due to the mesh structure it still provides good levels of security

This is the type of rack that is considered

modern computer rooms

modern comouter rooms

Some type of racks come with| casters of feet at the base of the rack

This creates a point load on the floor and as previously discussed

it is: therefore, not always desirable

hich have their frame as the base of the rack, are bet

since they fit nicely on the floor.

and create a reasonable distribution of the weight load of the rack,

Especially when the width of the rack is matching the floor tile dimension

If you are using casters or feet

be aware that there will be a gap between the rack and the floor.

which potentially creates leakage in terms ot cold and hot air

from the front and the back of the rack

To prevent the mixing of cold and hot an which will result in inefficiencies

you should consider closing this gap by using skirting at the base of the rack

and therefore, closing the gap between the floor and the rack

This is definitely a requirement when you are deploying containment solutions

Containment will be discussed in the cooling infrastructure module

Racks are commonly black or white in color

with some variants like grey or vanilla style color

Most data centers like to use the black color racks

since it looks nice in a computer room

Realize however, that while doing so it does impact the overall light strength

especially in the lower part of the rack

So looking from a light perspective

it is, therefore, better to use white color racks

this since white is reflective

In addition, it may introduc savings on the lights

being used in your computer room

All racks are ideally locked

both the front and the back to provide adequate security

Some data center managers may argue that the computer is already secure?

and therefore racks no longer have a need to be individually secured

Although this may sound logical

the question is whether anybody who comes through the computer room door

is allows to touch any equipment in any rack within the computer room

If such is not the case all racks must be blocked

Realize that in an operational data center on regular occasion

external staff is working in the computer room

and this could pose a risk

By default, a rack that comes with the lock is based on a key

whereby one key fits all

If requirements exist

you may have a need for , to avoid that

one single key opens all racks

but do realize that with many keys available

key management may become a nightmare

As an alternative you could consider using electronic locks

such as locks with the security pin coder

biometrics, which is a unique part of the body for authentication

and access card or other electronic means

This will be easier to manage and monitor

since every entry into a rack can be recorded in the log file,

which will allow you to track and trace

who had access to the rack and when the access occurred

As you can imagine electronic locks provide great functionality

but ther are more costly han the traditional key locks

Flower rails or power strips as they are often referred to

come in a wide variety of types each with their own functionality and price tag

It is important to understand the business requirements

before deciding on the strategy for purchasing power rails

Remember that each rack has at least one but more often two or four power rails

hence, every dollar extra per power rail can quickly add up to a large amount

One type of power rail is the one with the traditional standard power outlets

these rails provide only connectivity

but provides no protection, measurements or other functionality

this type of power level is the

Another power rail option

is the one whereby each outlet has an indicator to whether the power is on/off

These power rails are commonly equipped with the fuse

to protect each individual outlet,

this could potentially ensure

that it the device creates a short circuit or overload

then it does not affect the entire power rail

Be aware that some types ot power plug already have a fuse protection built in

if so, the fuse protection in the power rail may not be required.

Another type of power rail is the one which has a built-in power meter.

these meters can indicate the various power parameters, such as voltage

ampere, the power factor and other useful parameters.

The high end type of power rails very likely has a network connection built in

which allows you to monitor and or control the power rail

Depending on the type of model

it may be able to monitor at the individual outlet level

this provides great functionality such as having a remote power cycling capabilities

and other useful features

Realize though that these power rails are much higher in cost

so given the total number of racks

and the fact that most racks require multiple power rails

it is easy to understand that the investment cost is quite substantial.

Power rails are available in various configurations, such as single phase

three phase and three phase input which is then split over

three individual parts of the railway single phase outlets

as well as some three phase output at any combination that you can think ot

These kind of power hills offer great flexibility

create a better balance

within the three phases inside the rack

F inally, there are some additional

Many racks have fan assemblies at the top of the rack

using these fans, however, should only be done when using glass door based racks

When you are using the ventilated doors, such as mesh doors

then you will need to turn those fans off

since they will disturb the tront to the rear air movement

For racks which are installed in seismic prone areas,

adequate measures need to be taken

If you are using bracing

physical securing of all items

you need to identify the type of connection or fixing options

that are available on the rack

In that case you also need to make sure

that the racks are meeting the seismic requirements

to handle the physical force which they may get exposed to.

Ranking panels will help in creating a good separation

between hot and cool aisles

and this will have a positive effect on energy efficiencies

flanking panels should be installed in every rack space

where there is no equipment installed

The metal panels tend to be more expensive? and could still conduct hot and cold air

since metal is a good heat conductor

expensive and provide good insulation

but you need to make sure that this type meets the local tire regulations

Make sure that your rack rows areas long as possible,

so to make the row act like a wall

this to prevent the mixing of cold and hot air to take place

And while doing so, you have to consider the local fire safety regulation

to make sure that escape paths are still in adequate

In this module, you have learned

that there are many choices available for equipment racks

rack you should consider

and that the type ot rack you should consider

depends on the ICT equipment

as well as the room layout

Different type of racks and doors have an impact on security, as well as cooling

Various types of security and power rail options are available,

each with their own options and characteristics

Investigate the business requirements

since often a computer is equipped with many racks and power rails

so every dollar more per rack

or power rail will result in a much larger investment requirement

Energy Storage

This slide demonstrates data from research

which presents the influence of environmental factors

and the impact it has on electrons components on a printed circuit board

As can be concluded

temperature and humidity are the factors creating a major part of the problems

for reliability of electronics

Cooling is the number one issue in today's data centers, and in some cases

there is little understanding present on how to properly control the data center

Lack of proper cooling in the computer room is the result of a number of reasons

such as changes in the setup

issues created along the life cycle of the data center

misunderstanding of cooling principles, etc etc

Traditionally

cooling takes up as much as 30% of the total power consumption of a data center

It is therefore not surprising that more data centers

are looking into how they can create a more efficient cooling infrastructure

in order to drive the power consumption down

which will result in cost savings as well as being more environmentally friendly

When cooling ICT equipment in a data center

two important factors must be considered

which are temperature and air volume displacement

looking at the temperature the American Society of Heating

Refrigerating and Air Conditioning Engineers shortly known as ASHRAI

the Technical committee 9 9 is guiding the industry

on the recommended and allowable temperature and humidity for ICT equipment

In 2011, ASHRAE indicated the recommended values for ICT equipment in the computer rcxxn

to be in the range of 18- 27 degrees Celsius

which is equivalent to 65-81 degrees Fahrenheit

The values are anticipated to be extended in the upcoming years

which will allow for more parts of the world to make use of free coolinq

It is a common mistake in data centers for operations staff to assume'

that the temperature, which is set on the air conditioner,

is the temperature which will be supplied to the ICT systems

This is incorrect

The temperature set point ot an air conditioner

is based on the return air temperature?

In simplified terms, the air conditioner measures the air intake temperature'

and matches it with the setpoint

This means that if you set the temperature to 22 degrees Celsius

equivalent to 72 degrees Fahrenheit

the air conditioner tries to cool the area in such a way

that the return temperature is 22 degrees Celsius

Therefore, this result in a much lower temperature leaving the air conditioner

which is the temperature of the air flow supplied to the ICT systems

Because of this; it is important to measure the intake temperature on the ICT equipment

which should be within the ASHRAE recommended range

and compare that with the return temperature at the air conditioner level

This may result, for example in the set point being 27 degrees Celsius

as the return temperature

whereas at the same time the ICT equipment is having an intake temperature

of 23 degrees Celsius

looking at humidity ASHRAE has made changes between the values

for the 2008 and 2012 standards

The current values are indicated in this slide

The low end moisture has been lowered to 9 degrees Celsius dew point

Be aware that a relative humidity below 40%

will increase potential issues with electrostatic discharge

shortly known as ESD

IT and network electronic equipment

IT and network electronic, equipment

IT and network electronic equipment

will suffer reliability problems as it heats up

And because of that, it is important to keep equipment at its proper temperature

This graph explains the expected lite span of a central processing unit or CPU

at different temperature levels indicated in temperature Celsius

The graph explains that the microprocessor

can operate in 95 degrees (Celsius environmental temperature

which is equivalent to 200 degrees Fahrenheit,

but if it would, it could not last more than a couple of years

A high temperature is fatal

since it will reduce the life span of the equipment

I here is some confusion about the temperature in the data center

Some believe that the ambient temperature in the data center

should be around 20 degrees Celsius or 68 degrees Fahrenheit

but this is not correct

Cold air needs to be delivered at the intake of the equipment.

and following ASHRAf

this means delivering a temperature that is between 18 and 27 degrees Celsius

or 65 to 81 degrees F ahrenheit

Hardware manufacturers are moving beyond fans and adopt cooling mechanisms

liquid cooling systems

such as radiators and liquid cooling systems

to avoid potential overheating

As a result of downsizing the physical size of computer equipment

today’s systems are getting so hot that it is almost impossible to cool it with air

With the microprocessor getting hotter and a significant smaller computer chassis

there is less ability or less volume of air being able to push through the system

Cooling capacity is expressed in many units, such as British Thermal Unit

shortly known as BTU

horsepower, ton, etcetera

In practice, it wouldd be easier if everyone' uses the same unit to measure heat

which is kilowatts

obvious, since power and ICT load

are dimensioned in the same unit of measure

and therefore it makes it easier to perform calculations

on the need for your cooling

There are two types ot heat loads known as sensible heat and latent heat

Sensible heat is the type ot heat load

that causes a temperature

In the context of a data center

an ICT system heats up due to power entering the system

During this process, there is no moisture involved

Therefore, sensible capacity

is described as the capacity to lower the temperature in an object

The other type of heat load is called latent heat

I atent heat load causes a substance to change a state

An example is boiling water, which when water reaches boiling point

the water will evaporate into steam

Humans are also creating latent heat

as they produce heat and moisture

Think of working out in the gym or jogging in the park

which causes the body to heat up and throwing out moisture

which is the body transpiration

Comfort air conditioners have a low sensible heat load capability

These types of air conditioners are commonly used in areas where humans are present

and humans generate latent heat

A comfort air conditioner has no humidity control

and therefore lacks the capability to manage the humidity in an area

With the objective of cooling areas occupied by humans

comfort air conditioners are not designed for continuous operations

running twenty tour hours per day

The filter sections in this type of air conditioner are commonly more aimed at

protecting the internals of the air conditioner itself

rather than protecting its target area trom dust

and hence they lack the proper filter capabilities for computer rooms

Furthermore, these units normally lac k the control and monitoring interfaces

unless additional sensors are installed

Also,these units normally don’t have a control input

which allows the unit to be shut it down remotely.

This is a potential issue in situations such as a fire in an area

where the air conditioner equipment needs to shut down

before a discharge of fire suppression gas takes place

Precision air conditioners are designed for areas such as a computer room

They have a high sensible heat load capability,

which matches very well the type of heat that is generated in the computer room

Precision air conditioners are equipped with

a controlled temperature and humidification capability

and are therefore able to provide prec ise

and stable cooling and humidity capabilities

These units are equipped with proper filters,

which not only protect the air conditioner equipment itself

but it also often provides adequate filtering for the computer room as well

Also these units are designed and manufactured for continuous operation

which meets the requirements of the computer room

where your ICT equipment is also operating 24/7

Furthermore, precision air conditioners are commonly equipped

with very good monitoring interface capabilities

allowing high level interfacing

so that various parameters can be remotely monitored

For fire scenarios, they also have an emergency "power off interface contact

which allows you to connect the air conditioner unit,

to the fire detection panel

and therefore shutdown the air conditioner automatically

before the discharge of fire suppression gas takes place

This slide explains the four main components of an air conditioner

The evaporator consists of a grill through which some form of cold liquids

usually a refrigerant is flowing

On one side of the grill

warm air is coming in and it is passed through the grill

after which the heat will be extracted

As a result it will be cool on the backside of the grill.

The laws of energy dictate that the energy can’t just appear or disappear

It is always transforming so the heat that is rejected through the evaporator

has to go into another medium

That process is handled by the condenser

This is the unit that transforms the extracted heat into another medium

which is commonly in the open air

The compressor keeps the refrigerant flowing through

the system at specific flow rates and pressure

whereas the expansion valve controls the quantity of the refrigerant

that is flowing into the evaporator

A refrigerant is a chemical compound that is used as the heat carrier

which changes from gas to liquid and then back to gas in the refrigeration cycle

Refrigerants are used primarily in refrigerators

freezers, air conditioning but also heat pumps.

Refrigerants play a key role in cold production

Refrigerant with a phase change from liquid to vapour

receives the heat required trom a substance at a low temperature

to change its phase, and so produce cold

With the phase change from vapour to liquid

the refrigerant also transfers its phase changed heat

to another substance at a higher temperature

Regulations may restrict the use of some types of refrigerants

due to their toxicity, flammability their contribution to ozone layer depletion

and their impact on climate change

Freon is a brand name

but it is also a generic descriptor of a fluorocarbon refrigerant

R22 is banned in the United States and the European Union

but still in use in developing countries

It will be phased out by 2040 due to its Global Warming Potential (GWP)

and low ozone depletion characteristics

R410a is considered the alternative for R22

It is well used in data centers and it is considered more environmentally friendly

It does not contribute to ozone depletion

but it does have a Global Warming Potential.

Under the assumption that preventing ozone depletion is more important

in the short term than global warming potential for the short term

R410a is preferable to R22

Refrigerants are greenhouse gases and influence global warming

How much a greenhouse gas influences global warming depends on 3 key factors

The first is. how much of it exists in the atmosphere?

The second is its lifetime how long does it remain in the atmosphere?

The third is. how effective it is at trapping heat?

This is referred to as its global warming potential

which is a measure of the total energy

that a gas absorbs over a given period ot time

usually hundred years relative to the emissions of one ton of carbon dioxide

Arguably, therefore, the less (Global Warming Potential a refrigerant has

the better it is for the environment and long-term sustainability.

Air cooled and self contained units are normally ceiling cassettes

which hang on the suspended ceiling or are wall mounted

There are two types available

One type still needs a condenser unit outside ot the building

the other as the condenser unit built into the system,

and it just evaporates the hot air on top ot the suspended ceiling

Although relatively cheap to purchase

this type of air conditioner comes with a high operating costs

For the various reasons mentioned

this type of air conditioner is not recommended

for cooling ICT equipment in a data center

of air conditioner is known as a split system or DX system

which is short for Direct Expansion

This unit is commonly referred to as a computer room air conditioner or CRAC

or Heating and Ventilation Air Conditioner

shortly known as HVAC and it is based on refrigerant

The evaporator is in the data center

and from there pipes run to the condenser unit outside the building

Where the building code applies

you should verify if it is allowed to install this type of unit

because certain building codes do not alow

to place condenser units outside the building

Another potential issue

run.

The distance between the CRAG inside the data center

to the condenser outside ot the building

should not exceed more than 30 35 meters or 90 teet measured horizontally

Exceedig the length of the pipe run will result in

the air conditioner losing out ot cooling capacity

Some vendors are able to have a longer pipe run,

but you would need to review the technical specifications

to ensure that the pipe run length is matching the technology deployed

Scalability is relatively easy

so as long as you have floor space available

These units can be easily expanded by adding an additional unit in the room

and an additional condenser outside ot the building

Obviously adding additional units

in a production data center comes with certain risks

which needs to be addressed as part of the change management procedure

This type of air conditioner is different

instead of being freon based it is using glycol instead

One property of glycol is that it does not freeze

and therefore this type ot unit is very suitable in climates

where the winter temperature falls below zero

Again, where building code applies

verify if you can install a glycol based system

I onger pipe runs are possible since pumps can be added in the middle

but it adds to the cost

One condenser unit can feed multiple? CRAC units inside the data center

and this is an advantage if there is a shortage of space

But combining multiple CRAC units making use ot a single condenser

results in that the same condenser to become a single point of failure

So if the condenser fails

it may take down multiple CRAC units

Completed. Let's continue.

Chilled water based systems provide a high efficiency rate within the data centra

In a shared building where space is commonly used for office purpose

it needs to be verified if the building has the capability

to supply enough chilled water to cool the data center

Similar if maintenance or failure appears

is the remaining level of chilled water capable

of supplying sufficient cooling capacity

such that the data center will not suffer

Building owners sometimes charge on the amount

of water measured in a unit or time frame

and this may become an issue during the renewal ot the rental agreement

whereby an increase of the water price

may have a drastic impact on your operational cost

Therefore contract terms and conditions need to be studied carefully

In situations where you own the data center

chilled water based systems come with a high initial cost

and redundancy needs to be looked into as a result of a possible chiller failure

Instead of using computer room air conditioners

this system mates use of computer room air handlers

To provide cooling, an air handler uses chilled water and a control valve

whereas an air conditioner uses refrigerant and a compressor

This slide demonstrates the type of hybrid air conditioning system

with a mixture ot a chilled water circuit and a direct expansion system

The air conditioner unit is equipped with two evaporators in a single unit

Under the normal conditions the chiller system is operating

supplying cold water to the chilled water circuit