What is “Quick Removal” and How is it Changing in Windows 10?

Microsoft recently made an announcement that as of Windows 10 version 1809, the default for the “Quick removal” setting would be changed.

The pragmatic result is that you should see or need to use “Safely Remove Hardware” less often.

Let’s look at why that is.

Removal considered harmful1

Removing or unplugging an external drive from your computer while everything is turned on can be risky. If anything is being written to the disk at the same time you unplug it, you run the risk of corrupting the data stored on the drive.

Unfortunately, this is at odds with a speed optimization that can make it look like your computer has completed writing data to the drive, when it has not.

Pull the plug at the wrong time, and bad things happen.

Write caching

Write caching is a technique used by many computers and device drivers to collect data in RAM (in a ‘cache’) to be written to a disk before writing it. This way, the device driver can tell the program requesting that the data be written, “I’ve got it”, and that program can do other work without waiting for the write to finish. Windows completes the write to disk in the background.

You might see this when you perform a save operation with a large file. You click on “Save” and it seems to happen very quickly, perhaps almost instantly. But if you look closely, the light on your external drive (if it has one) might still be flashing for a while as the data is transferred in the background.

By not forcing the program to wait until a write has completed, the program — and, indeed, the entire computer — operates more quickly.

Write caching is a speed optimization designed to make your computer more efficient.

Quick removal

“Quick removal” turns off write caching.

That means that the program doing the writing must wait until the data has been written to the device before it can move on to other things.

In this case, when you click “Save” on that large file, it’ll take longer. You’ll have to wait until the file has been saved before you can move on. You’ll likely see the lights on your external drive stop flashing right around the same time the save operation completes.

Quick removal is safer because you’re less likely to think that writing has completed when it’s still underway.

Safely remove hardware

The Safely Remove Hardware item in your Windows Taskbar notification area is, in concept, very simple.

By clicking on “Safely remove” for a specific device, you force Windows to complete all the cached writing that might be underway.2 Once complete, you get the familiar “You may now remove…” message for whatever device you request.

Changing the default

When an external drive is connected, Windows has to decide whether to enable write caching or not.

In the past, for many (if not most) drives, the default was to enable write caching, and therefore require the use of “Safely Remove” before the drive could be removed.

With Windows 10 1809, the default has been changed. In more cases, Windows will not enable write caching, opting instead for “quick removal”.

You can see and change what Windows has selected for your drive. With the drive attached, right-click the Start Menu, click on Disk Management, right-click on the Disk representing the drive, click on Properties, and then click on the Policies tab.

“Removal policy” indicates the current setting. You can change it if you like, and click OK.

The practical impact

On modern machines, the benefits of write-caching on external USB drives is minimal. On older machines, write-caching probably had more of an impact (perhaps most with the older, slower, USB 1 interface). With USB 3 (and even USB 2 to a large degree), the data is written fast enough for the additional caching to have little, if any, practical effect.

Not having to worry about “Safely remove” is probably of more benefit, as it reduces the risk of data loss by pulling the plug at an inopportune time.

To be clear, pulling a device while it’s being written to is always a bad idea and can result in corruption and data loss. “Quickly remove” just makes it less likely for the device to look like it’s done when it’s not.

If you see “safely remove hardware” present for a USB device, that device probably does not have “Quick removal” turned on3. If “Quick removal” is enabled, you’ll generally not need (or see) “Safely Remove Hardware”.

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Footnotes

1: “Considered harmful” is almost a meme in computer circles, dating back to 1968.

2: It almost certainly looks at other things, like open files on the device, but the primary function is to make sure pending writes are complete.

3: Or, it appears, the device is complex enough that, for whatever reason, it still requires “Safely remove” to be present. I have at least one device that still appears in “Safely remove”, even though it’s marked as “Quickly remove”. I do not get a warning if I remove without using “Safely remove”, however.