Q.1 This
question is about components of data centre and data centre standard.
(a) The following shows the power usage of
components in a data centre. Find the
Power Usage Effectiveness (PUE) for this data centre. Then, comment on the energy efficiency of this
data centre. [5 marks]
Uninterruptible
power supplies (UPS) system = 3,000 KW (a)
Power
redundancy system = 2,000 KW (b)
Storage
equipment = 5,000 KW (c)
Cooling
system = 10,000 KW
(d)
Lighting
= 5,000 KW
(e)
Servers
= 65,000 KW
(f)
Networking
devices = 10,000 KW (g)
Ans:
IT
equipment power = c + f + g = 80,000 KW [1 mark]
Total
power = a + b + c + d + e +f + g = 100,000 KW [1 mark]
PUE
= (a + b + c + d + e +f + g)/(c + f + g) = 1.25 [2 marks]
The value of PUE is less than 1.5, so the energy performance
of this data centre can be regarded as efficient. [1
mark]
(b) Identify the missing names of areas in
the schematic diagram of a data centre shown in the following figure. Identify also the cabling to be used with
labels L1, L2 and L3 respectively. [11
marks]
(c) Apart from
IT services, a data centre must provide the following services to support the
operation of IT services. List two
particular examples in each of the following services: [6 marks]
(i) Physical security and access control
(ii) Fire protection
(iii) Power supply protection
Ans:
(i)
7 x 24 Guard service, Video surveillance, Biometric access
(ii) Smoke detector,
pre-action water, FM-200 gas suppression system
(iii) Redundant
uninterruptible power supply (UPS), emergency generators
Q.2 This
question is about networking.
If a question asks you write commands for a
network device, you can assume that the device is at the global configuration
mode.
(a) You would like to enhance the network
infrastructure with link aggregation.
(i) Briefly
describe TWO benefits of this solution.
[4
marks]
Ans:
l
Increased link
bandwidth –
Within each link aggregation group, traffic is
distributed across the member ports according to a certain algorithm. Link
aggregation thus increases the link speed beyond the limits of any one single
port.
l
Enhanced link
reliability – The member
ports in a link aggregation group dynamically back up one another. When a
member port fails, its traffic is automatically switched to other member ports.
(ii) What is
the corresponding technology adopted in Cisco switches? [2
marks]
Ans: EtherChannel
(iii) Draw a
connection diagram to show your updated network infrastructure after
introducing link aggregation. [3
marks]
Ans:
(iv) Write the
commands to add ports Fa0/7 and Fa0/8 to port channel 1 in DLS1 with IEEE’s
negotiation protocol. Configure also the
ports to be in trunk mode with IEEE 802.1q. [4
marks]
Ans:
interface range fastEthernet 0/7 - 8
switchport trunk encapsulation dot1q
switchport mode trunk
channel-group 1 mode active
(v) What is the Cisco command used to
verify link aggregation is working? [1
mark]
Ans: show etherchannel (summary)
(f)
(i) What is Virtual Ethernet
Bridging (VEB)? [1
mark]
Ans: A VEB is
basically software that acts similar to a Layer 2 hardware switch providing
inbound/outbound and inter-VM communication.
(ii) List THREE weaknesses for using Virtual Ethernet
Bridging (VEB). [3
marks]
Ans:
·
Use CPU
computing power, less CPU power will be left to virtual machines.
·
The
communications between vNIC clients within one hypervisor are not visible to
the outside world.
·
Virtual machine
network access control strategy is not easy to implement.
Q.3 This
question is about servers and server virtualization.
(a) There are two major form factors in
servers using nowadays. One is blade
server and the other is rack server. Briefly
explain two advantages and two disadvantages of using blade servers comparing
with rack servers. [4
marks]
Ans:
Any
two of the following advantages, each 1 mark:
l
Space – Rack servers are larger and require more real estate in a
datacenter. Blade servers are more
compact, utilize less space.
l
Computing Power – Rack servers consume more power due to their size and
because they are harder to cool. Blade
servers usually have built-in fans and cooling capabilities that can save on
expenses.
l
Cabling – A blade
environment generally has less of cable than rack environments since a lot of the
connectivity is handled internally.
Disadvantages,
each 1 mark:
l
Cost – Blade servers are usually more expensive. They require some
initial infrastructure, such as the chassis.
l
Internal Storage Size - Many blade servers are limited to two to
four internal hard drives.
(b) What
is the function of hypervisor and what are the two types of hypervisor?
What are the differences between these two types of hypervisor? Give
two examples for each type of hypervisor.
[10 marks]
Ans:
A hypervisor is a piece
of computer software, firmware or hardware that creates and runs virtual
machines.
[2 marks]
l
Type 1 or bare metal hypervisor [1 mark] - this type of hypervisor runs
directly on the host's hardware to control the hardware and to monitor guest
operating systems [1 mark]. A guest
operating system runs on above the hypervisor [1 mark]. E.g. ESXi, Hyper-V, KVM
[1 mark]
l
Type 2 or hosted hypervisor [1 mark] - it runs within a conventional
operating system environment [1 mark]. With the hypervisor layer as a distinct
second software level, guest operating systems run at the third level above the
hardware [1 mark]. E.g. VMware
Workstation, VirtualBox, QEMU [1 mark]
(c) State the advantages of using type 1
hypervisor. [5
marks]
Ans:
l
The hypervisor has direct access to the Hardware. Guest OSs do not need to make processor,
memory and I/O requests via a host OS as in type-2. The processing is much faster.
[2 marks]
l
System is thin. This allows us to give most of the physical resources to
the virtual machines.
[1 mark]
l
Decreased security attack vectors so that the system is harder to
compromise.
The number of VMs on a host can be
higher. [1
mark]
l
The number of VMs on a host can be higher. [1 mark]
(d) When John
configured the server, he found the following terms in the BIOS settings of the
server but he didn’t know what they meant.
Explain to John what these terms represent and the benefits of using
them.
(i)
Intel VT-x [2
marks]
(ii)
Intel VT-d [2
marks]
(iii) Intel
VT-c [2
marks]
Ans:
(i)
VT-x represents Intel's technology for virtualization on the x 86
platforms. [1 mark] It speeds up the transfer of platform control between the
guest operating systems and the hypervisor. [1 mark]
(ii) VT-d stands for
"Intel Virtualization Technology for Directed I/O". [1 mark] It enables the hypervisor to uniquely
assign I/O devices to guest OSs. [1 mark]
(iii)
VT-c represents virtualization technology for connectivity. [1 mark] It improves the performance of
network I/O on a virtualized system. [1 mark]
Q.4 This question is about data storage and its
infrastructure.
(a)
What are the two most commonly
used interface for mechanical harddisk nowadays?
[2 marks]
Ans: SAS and SATA
(b)
Name two advantages and weaknesses of SSD comparing with mechanical HD? [4 marks]
Ans:
Advantages: SSDs are less susceptible to physical shock,
silent
and have
lower access time and latency.
Disadvantages: SSDs are more
expensive.
SSD failures
are often catastrophic, with total data loss.
(c)
There are 3 types of common storage infrastructure solutions you can
choose. What are they? Briefly describe when to use each of them. [10
marks]
Ans:
l
Direct Attached Storage (DAS) – It is ideal for local data sharing
requirements. It is a low cost solution
for home computers and small business.
l
Network Attached Storage (NAS) – It provides heterogeneous file-level
data sharing across the enterprise. It
is a cost-effective solution.
l
Storage Area Network (SAN) – It provides fast block-level data transfer
while reducing I/O latency and server workload.
It is the best way to ensure predictable higher levels of performance
and 24x7 data availability and reliability.
So it is deployed in data centres.
沒有留言:
張貼留言