Physical servers and storage behind the cloud

Name:

Date:

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Quick Questions

Shade in the A or B circle for each question.

1. Where is data stored when you use cloud storage?

A On storage devices in a data centre owned by the provider

B In the air or on the internet itself, with no physical hardware

2. What is a data centre?

A A building full of servers and storage devices

B A single USB drive that is plugged into the user's computer

3. Who owns and maintains the hardware used for cloud storage?

A The customer who saves files there

B The cloud storage provider

4. Which statement about cloud storage hardware is correct?

A One single hard disk holds all of the customers' data

B Many servers and storage devices work together to hold the data

5. Why do providers often keep copies of your data in several locations?

A So data is not lost if one device or data centre fails

B So the data takes up less storage space

Match the Pairs

Draw a line connecting each item on the left to its match on the right.

Left column		Right column
1data centre		Aprovider.maintain(servers)
2replication		BA building full of servers and storage devices that hold the data people save to the cloud
3The cloud provider owns, powers and maintains the physical hardware, not the user		CCloud data is not stored in the air. It is held on physical servers and storage devices in data centres.
4Cloud data is held on many storage devices and servers working together in a data centre		Ddata_centre = [server1, server2, server3]
5cloud_data = "stored in the air, no hardware"		ECopying data to several storage devices or locations so it is not lost if one fails
6copies = 1 # only one copy of the data, so it is always safe		FKeeping only one copy is risky. Providers usually copy data to several locations in case a device or site fails.

Definitions

data centre

Fill in the Blanks

Complete each line of code by filling in the missing parts.

A ___________ is a building full of servers

The ________ owns the cloud hardware

Data is often ______ to several locations

Users reach a data centre via the ________

Cloud data is held on physical _______

Spot the Error

Shade in the letter of the line that contains an error.

Question 1

A provider = 'CloudCo'

B owns_hardware = False

C location = 'data centre'

Question 2

A servers = 500

B drives = 24

C total = servers + drives

Question 3

A copies = []

B for site in ['UK', 'USA']:

C copies.remove(site)

Question 4

A def store(file, sites)

B for s in sites:

C print('Saved to', s)

Question 5

A data_centre = []

B data_centre.add('server1')

C data_centre.append('server2')

D print(len(data_centre))

Answer Key

Physical servers and storage behind the cloud

Section A: Quick Questions

A — On storage devices in a data centre owned by the provider

A — A building full of servers and storage devices

B — The cloud storage provider

B — Many servers and storage devices work together to hold the data

A — So data is not lost if one device or data centre fails

Section B: Match the Pairs

data centre → A building full of servers and storage devices that hold the data people save to the cloud

replication → Copying data to several storage devices or locations so it is not lost if one fails

The cloud provider owns, powers and maintains the physical hardware, not the user → provider.maintain(servers)

Cloud data is held on many storage devices and servers working together in a data centre → data_centre = [server1, server2, server3]

cloud_data = "stored in the air, no hardware" → Cloud data is not stored in the air. It is held on physical servers and storage devices in data centres.

copies = 1 # only one copy of the data, so it is always safe → Keeping only one copy is risky. Providers usually copy data to several locations in case a device or site fails.

Section C: Definitions

data centre — A building full of servers and storage devices owned by the cloud provider. It holds users' data, often copied to several locations, and is accessed over the internet.

Section D: Fill in the Blanks

A data centre is a building full of servers

The provider owns the cloud hardware

Data is often copied to several locations

Users reach a data centre via the internet

Cloud data is held on physical servers

Section E: Spot the Error

B — In cloud storage the provider owns and maintains the servers and storage devices. The line should be owns_hardware = True.

C — If every server holds 24 drives, the total number of drives is servers multiplied by drives, not added. It should be total = servers * drives.

C — Data is often copied to several locations, so each site should be added to the list of copies. remove would fail on an empty list. It should be copies.append(site).

A — A function definition must end with a colon. The line should be def store(file, sites):

B — A Python list has no add method. To add a server to the data centre list you use append: data_centre.append('server1').