Operating Systems · Storage and I/O

Hard disks and SSDs

How spinning disks and flash storage actually store and retrieve data, and why their performance shapes differ.

Also known as: disk scheduling, seek time, flash storage, SSD.

Start a lesson on Hard disks and SSDs

Learn first

• I/O devices and interrupts: How the OS talks to devices, through polling, interrupts, or DMA, without the CPU babysitting every transfer.

Leads to

• The file system abstraction: Files and directories as the OS's user-facing model, sitting on top of raw disk blocks.
• Redundancy and RAID: Spreading or duplicating data across multiple disks so one drive failing doesn't lose data.

Related topics

• Redundancy and RAID: Spreading or duplicating data across multiple disks so one drive failing doesn't lose data.