Data Centres, Server Software, Virtualisation Flashcards
What is the cloud?
A large collection of servers that can be accessed via the internet, paired with software that runs on them
What does on-premises cloud or “on-prem” cloud mean?
When Companies build/own/host their own private cloud
Where do servers that are part of the cloud live and who offers them as part of a service?
They live in datacentres, which are owned by cloud providers such as AWS, Microsoft Azure and Google Cloud.
- Individuals or companies can rent out sections of the cloud from these companies as a service.
Give some examples of uses of the cloud?
- e-commerce
- website hosting
- storage of AI resources/processing power
- Software as a service: Google Documents, Microsoft office
What is E-Commerce?
The buying and selling of goods (physical items) and services (digital goods like movies/streaming) over the internet
What is a datacentre?
A big warehouse of servers / other network devices.
- Requires a powerful cooling system
What does a server rack consist of?
- Servers
- Network switch (allows servers to communicate, plugs into the wider network)
- Cooling system (pumps in cool air and pumps out hot air)
What are data centres built from?
- Commodity hardware: Hardware you can buy from Amazon. Relatively inexpensive, available and off-the-shelf hardware.
Describe servers and their components:
Servers have CPUs, RAM, hard disks, NIC (no I/O components)
- Servers are typically rack mounted and connected a network switch.
Describe top of the rack switches
They are used to connect each server to other servers in the same rack. It also connects servers to the data centres network.
Describe the difference between a local network (LAN) and the internet:
A small group of computers form a network that is limited to a small area (a house or office building)
- this is owned, managed and maintained by a single organisation
Describe what NICs are
Network Interface Cards allow hardware components to connect to a network. Any component that connects to a network has a NIC.
- Every NIC has a MAC address which is assigned when the NIC which is assigned when the NIC is made and uniquely identifies it.
Describe what a MAC address is:
The MAC is a known as a burned-in address as it used to be physically burned into the NIC. Nowadays the address is hardcoded into the NICs software (sometimes it can be modified).
Describe the format of a MAC address:
It had 6 pairs of hexadecimal digits (0-E)
- first 3 pairs represent the OUI (belongs to the manufacturer of the NIC)
- last 3 pairs represent a NIC-Specific identifier
Describe what network switches do:
- They connect devices within a single computer network.
- They connect computers within a LAN to facilitate communication within a network
Describe what routers do:
- They connect multiple networks together
- they direct traffic between networks.
Describe what firewalls do:
- They are network security devices that sit on the boundary of a network to monitor and filter incoming and outgoing traffic.
- They protect LANs by examing each packet of data to determine whether it should be allowed into the network or blocked, based on a set of rules.
- it’s able to block specific ports or requests and allow others through
- It can be either software or hardware.
What software runs on servers?
- They run operating systems
What do Operating systems do?
- They manage computer hardware and software resources and provide them in an accessible way to other computer programs
- they allocate resources like CPU, memory and I/O devices
- control creations, deletion and access of files
- offer a UI, GUI or CLI
Which OS do servers mostly use and why?
- They mostly use Linux, as it’s free and open source
What are some distributions of the Linux OS and why might they be used.
Which distribution is typically used for cloud servers.
- it’s available in multiple distributions: RHEL, Ubuntu, Fedor, Debian and CentOS
- Each distribution is tailored to specific use cases and user preferences.
- Cloud servers typically use RHEL
Describe what the linux kernel is:
(the heart of the linux OS)
- It manages hardware resources and provides essential services to the software that runs on it
- when an application wants to access hardware, it makes a request to the kernel which handles this
Describe some functions that the Linux kernel performs:
- Process management: handles creation and termination of memory
- memory management: manages memory allocation and deallocation
- device drivers: interacts with hardware through device drivers
Describe the kernel space
- Where the kernel operates
- code running here has complete access to the hardware. This introduces security issues, so it’s run in a protected memory area, ensuring stability and security.
