storage 5

International & Access Foundation Programmes

• This programme includes a Computer Science Module.
• The module covers Semester 1, Part 6, focusing on Networks: PC Internals, Storage, and Network Storage.

PC Structure

• A computer system has input, processing, and output components.
• Input devices include keyboard and mouse.
• Processing is handled by the processor (chip).
• Output devices include monitor and printer.
• Storage devices such as hard drives and flash memory are also crucial parts of the system.

Inside a PC

• Components like the CPU, RAM, CPU cooler, motherboard, graphics card, PSU (power supply unit), and hard drive reside inside the computer case.
• Different bays exist for different components (5.25", 3.5").

Motherboard

• The motherboard is a crucial component inside the PC.
• It features DRAM memory slots, a power connector, CPU heat sinks, CPU socket, Northbridge, and Southbridge.
• ROM chips, PCI slots, AGP slots, and connectors for peripherals (like audio, ethernet, serial ports, and USB) reside on the motherboard.
• The northbridge and southbridge control data flow and communication between different components.

DDR RAM

• DDR SDRAM (Double Data Rate Synchronous Dynamic Random-Access Memory) versions (DDR, DDR2, DDR3, DDR4, and DDR5) have different release dates, bus clocks, voltages, transfer rates, and prefetch (burst) rates.
• These specifications reflect technological advancements and improved performance.

RAM

• Random Access Memory serves as temporary storage for active programs and data.
• Data lost on power off.
• DDR RAM types differ in speed and capacity.

CPU Cache

• A CPU cache is a small, fast memory area within the CPU itself.
• It stores frequently accessed data from main memory to speed up data access.
• Several layers (like L1, L2 cache) exist to make the process increasingly quicker.

Paging

• Paging is a method to access more memory than the physical RAM capacity.
• It moves inactive data to the hard disk (swap file).
• Recent or active data remains in the RAM to increase the speed.

Swap File

• Swap file is a portion of the hard disk used as virtual memory.
• Data moved from RAM that is not needed immediately gets stored to the hard disk for space and efficiency. It is retrieved back to RAM later if needed.

Optical Storage

• Optical drives (like CDs and DVDs) use laser to read and write data.
• Data recorded in binary pit patterns that the laser reads to retrieve data

Making Disk Storage Reliable

• Hard drive failure can lead to total data loss, hence regular backups are essential.
• RAID (redundant arrays of independent disks) a technique to prevent this data loss from hard drive failures and provide high data availability.

RAID Levels

• RAID 0 is data striping across multiple disks for read/write performance improvements. No redundancy-less data availability
• RAID 1 is a mirroring technique, where data replicated across multiple disks. Good read/write performance, high redundancy
• RAID 10 combines striping and mirroring techniques to combine benefits.

Network Attached Storage (NAS)

• A network storage device for file sharing.
• NAS devices perform file sharing and other essential tasks, like email management and authentication, but not overall server operations.
• NAS allows adding hard disks without computer downtime for maintenance.

Storage Area Network (SAN)

• Standalone network to manage storage.
• A SAN is a storage network separate from the primary network; it connects storage devices without affecting primary network usage, hence no network slowdown.
• Fiber Channel is a typical SAN network architecture.

Cloud Computing

• This is a networked computing model running on the internet, hosting computing services and resources.
• It is a platform that handles hardware and software required for service provision.
• Resources used and paid for on a pay-as-you-go basis.

Software as a Service (SaaS)

• Software delivered over the internet, instead of locally installed.
• Cloud providers host the software and related services/infrastructures (maintenance and updates).
• Users access the software through the internet browser of the computer and other devices.

Cloud Delivery Models

• SaaS-software as a service, PaaS-platform as a service, IaaS-infrastructure as a service
• SaaS is the user-software interface, PaaS hides the platform infrastructure, and IaaS delivers the physical infrastructures that form the cloud

Cloud Storage

• Cloud computing allows access and usage of storage services on any device connected to the internet.
• Web providers manage the underlying storage systems remotely, delivering storage services.