Defragmentation

On traditional spinning hard disks, files can become fragmented. Fragmentation slows the system down but can be repaired by running an operation called defragmentation.

Do NOT defragment an SSD!

Defragmentation can actually harm SSDs and decrease their lifespan. This is because SSDs do not store files contiguously anyhow, but they DO have a limited number of write cycles, and the defragmentation process will use up write cycles (with no benefit).

Fortunately, Windows 11 offers a "disk optimization" tool that intelligently selects defragmentation (HDD) or trimming (SSD): See https://www.xda-developers.com/how-defragment-windows-11/

Two important concepts are introduced in the 3-minute video clip below:

The concept of slack (sparsely occupied clusters, like sparsely occupied houses in our analogy)

Analogy: Slack is like underutilizing the space in a house

A house can be full of people or have few occupants. Our goal is to accommodate as many people as possible, so we try to fill each house and avoid underutilizing the space (having too much slack).

The concept of linked allocation

Analogy: Linked allocation is like mail forwarding

Sometimes a letter is delivered to an address, but the actual recipient has moved on! With linked allocation, you can imagine that someone in the house knows where the mail should be forwarded, and forwards it to the appropriate address. Mail forwarding works, but it is slow and cumbersome.

Filesystems (10 pts)