# The copy says done. Can you just pull the USB stick out?

- Series: [How Computers Work](https://miu.fm/howcomputerswork.md)
- Published: 2026-10-29
- Page: https://miu.fm/howcomputerswork/the-copy-says-done-can-you-just-pull-the-usb-stick-out

## Story

The copy says done. Can you just pull the USB stick out?

I timed a write on a laptop (to its own drive): a 1 MB file said done in 0.12 ms, but the drive only really held it 4.4 ms later, over thirty times longer (median of seven runs, this morning).

Writes don't go straight to the drive. They land in memory first and the drive catches up a moment later: write caching. It makes saving feel instant, but pull the drive out in between and what was still in memory never arrives. Microsoft's own warning: "If you remove or disconnect the device without following the safe removal instructions, you risk losing data."

That's what eject (Safely Remove Hardware) is for: in Microsoft's words, it protects your data "by making sure that all cached operations finish". And beginning in Windows 10 version 1809, Windows uses Quick removal for external drives by default: it doesn't cache their writes, so the drive is "ready to remove at any time". So when nothing is copying, pull it. When you're not sure, eject.

The laptop, the stick and the memory blocks are our own simplified drawings.

Do you eject, or just pull?

Sources: our own measurement on a laptop, 2026; Microsoft Learn, Windows default media removal policy (2025).
Sounds and music: made by us.

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