3.3 Data storage

• Primary storage - is storage that is directly accessible by the CPU. it includes RAM, Cache and ROM.
• Primary storage purpose is to store data, instructions and software that are currently in use
• RAM (random access memory) is (volatile) memory that can be accessed randomly, storing data currently in use.
• ROM (Read only memory) - is (non volatile) memory that permanently stores important data and instructions. e.g. for the boot up
• volatile data - data that will be lost when the system is powered off
• Cache - small (volatile) memory that has really fast data access speeds for the CPU, used to store frequently used data.
• Secondary storage - stores data that isn't directly accessible by the CPU.
• Secondary storage is used to store permanent data
• SSD - flash memory (non mechanical) storage made up of transistors. It uses NAND and NOR gates to persistently control the flow of electrons
• defragmentation - the process of organising data so it is easier and faster to fetch
• Magnetic hard disk drive - A type of disk drive that uses a spinning disk to store data.
• a magnetic hard disk is made up of several metal discs coated in magnetic material. these are called platters.
• Optical data storage includes (CDs, DVDs and Blu-rays). they work by shining a laser at the disk and processing the reflection.
• Virtual Memory - secondary storage which acts as RAM when the RAM is full
• Cloud storage - data stored remotely on servers that are accessed via the internet.
• cloud storage is managed by cloud storage hosting companies.
• cloud storage is often stored on a server in a large warehouse full of servers
• cloud storage data can be accessed at any time and by any device on the network simultaneously
• (cloud storage) advantage - if you're not hosting the servers, you're not liable for loss of data or cyber threats