How to enable write caching on external drives and speed up transfers

If you frequently use external hard drives, USB flash drives, or SSDs portable When moving large amounts of data, you've probably been frustrated at some point when you see the progress bar go from flying by to crawling at a few megabytes per second. Write caching and system configuration make the difference between a smooth transfer and an eternally slow one..

In addition to the Windows write cache, other factors come into play such as the type of USB port, the file system, drivers, antivirus software, or even background processes you didn't even know were running. Understanding how all this works and fine-tuning it allows you to get the most out of your external drives and minimize bottlenecks..

What is disk write caching and why does it speed up transfers?

Write caching is a function by which the operating system It does not write the data directly to the disk at the same instant, but instead stores it first in memory (usually RAM). and sends them to the device storage more efficiently.

In practice, when you copy a large file to an external drive, Windows initially shows a very high speed because it's writing to RAM at maximum speed.Then, in the background, the system gradually empties that cache onto the physical disk. This mechanism reduces waiting times and improves the feeling of smoothness.

The problem is that That RAM that acts as a buffer is volatileIf the power goes out, the computer freezes, or you force a shutdown while there is still data in the cache waiting to be written, you can lose files or corrupt the file system of the external drive.

For this reason, Windows 10 and modern versions enable write caching by default only on internal disksWhereas on most external drives the default configuration prioritizes security (fast removal) over performance.

In summary, write caching gives you More speed in exchange for more risk if you don't eject the device correctly or experience power outagesThat's why it's so important to understand how it's activated, when it's worthwhile, and what precautions to take.

How to enable write caching on external drives in Windows

In Windows 10 and Windows 11The write cache on internal disks is usually enabled by default. However, on external drives (HDDs, SSDs, USB drives) it is usually disabled using the quick removal policy.Changing this policy is simple, although it must be done thoughtfully.

To modify the settings from within the system itself, Everything is managed from the Device administratorwhich is where Windows lists both internal and external USB-connected drives.

The basic procedure for enabling write caching on a specific drive is as follows, keeping in mind that tab names may vary slightly depending on the model or driver:

• Open Device Manager by right-clicking the Start button and choosing "Device Manager", or by pressing Windows + X and selecting that option.
• Expand the section «Disk drives» and locate the external drive you want to work on (SSD, HDD or USB memory).
• Right-click on the device and enter «Properties» to view its advanced settings.
• Within the window, go to the tab "Directives"This is where Windows allows you to adjust write and extract behavior.

In that tab, two different configurations may appear depending on the unit:

Many external hard drives will show two general policy options: "Rapid extraction" y "Better performance"The first option is usually selected by default and means that the device's write cache is disabled or limited, allowing you to unplug it without needing to safely eject it (although it is never recommended to do so abruptly).

If you select "Better performance"Windows enables write caching and may also display an additional checkbox such as "Enable write caching on device". By checking this box, the system will begin accumulating data in memory before sending it to the drive.improving speed, especially in intensive writing.

Some units directly display the box "Enable write caching on the drive" without the Quick Pull/Better Performance labels. In that case, simply select it, click OK, and restart if prompted by the system for the change to take effect.

It is important to keep in mind that Enabling this feature increases the risk of data loss if you disconnect the drive without always using the "Safely Remove Hardware" option.Or if your system frequently experiences sudden shutdowns. If your absolute priority is to avoid any possibility of corruption, you might want to keep the extraction fast.

Common causes of slow write speeds on SSDs and USB drives

Beyond write caching, there are many reasons why an external drive might run much slower than expected. In external SSDs, for example, it is relatively common to see high initial speeds that then plummet. at a few megabytes per second.

One of the key factors is the SSD's own internal architecture: Many models rely on a limited internal SLC cacheWhile that cache has space, the drive writes very fast; when it fills up, the true speed of the TLC/QLC cells becomes apparent and the write rate plummets.

Furthermore, an excess of data on the drive, the presence of bad sectors, or even malware This can cause widespread slowdowns. If the SSD is nearly full or has physical errors, the controller has to work harder, reorganizing data and managing remapping, which is noticeable with every large copy.

Nor should we forget the problems of eating: Some USB ports (especially 2.0 or cheap hubs) do not provide enough power for an external SSD to operate at maximum speed, causing performance drops or intermittent disconnections.

In the case of traditional external HDDs, mechanical factors also come into play: highly fragmented, full, or years-old discs They usually offer write speeds much lower than theoretical, and any vibration or impact can worsen the situation.

How to correctly measure the speed of your external hard drive

Before you go crazy messing with settings, it's good to know whether your unit is actually running slower than normal or if the speed you're seeing is within a reasonable rangeCopying a folder "by eye" can be misleading, because caches, file sizes, and other factors come into play.

Instead of resorting to commands complicated in the symbol of the systemThere are specific tools that reliably measure read and write performance. Disk partitioning and diagnostic programs such as EaseUS Partition Master, which includes "DiskMark" type functions that launch synthetic tests and give you sequential and random speeds.

This type of software is especially useful for inexperienced users, because They offer a clear interface, indicate which drive you are testing, and minimize the risk of accidentally deleting data.In just a few clicks you can check if your external SSD performs as promised by the manufacturer or if there is a serious bottleneck.

If you detect speeds significantly lower than the specifications, It's necessary to check both the hardware (cables, ports, USB type) and the Windows configuration.In some cases, simply changing the port or updating drivers will be enough to restore acceptable performance.

Another important detail when testing is the file type: Synthetic benchmarks typically use large, continuous blocksThese tests primarily represent the copying of large videos or images. If your actual usage involves many small files, it's normal for the actual speed to be significantly lower than what was measured in these tests.

Hardware: USB ports, cables, and drive type

One of the most common mistakes is connecting fast drives to hardware that isn't up to the task. If you plug a USB 3.0 drive into a USB 2.0 port, the actual speed will be limited by the slower standard.no matter how modern the SSD is or how good a cable you've bought.

The USB 2.0 protocol has a theoretical speed of 480 Mbit/s (about 60 MB/s), but In practice, you rarely exceed a sustained 30-35 MB/s.Most cheap USB 2.0 flash drives don't even come close to that figure. To truly take advantage of an external SSD, you need superior USB 3 ports and cables.

A good visual clue is the color of the connector: USB 2.0 ports are usually black, while USB 3.x ports are distinguished by the blue interior.In addition, many new devices include ports USB-C or even Thunderbolt, which offer even greater bandwidths.

The computer can also be the bottleneck. An old PC, with an outdated chipset or a poorly optimized USB controllerIt may not be able to handle sustained high speeds, even if the port is physically USB 3.0.

In this sense it is key Keep your motherboard and USB chipset drivers updatedWindows installs generic drivers that work, but they don't always offer the best performance. Checking the motherboard manufacturer's website and downloading the latest versions usually improves stability and transfer rates.

Windows software and settings that slow down writing

Not all speed problems originate from the hardware. Windows and its configuration may also be slowing down transfers without you noticing it at first glance, especially in equipment where nothing has been touched since installation.

The first step is to make sure that the system and drivers are up to date. Older versions of Windows or USB drivers may not be ready to take advantage of the new protocols.This translates into rates well below expectations even with good hardware.

Another prime suspect is the antivirus software. Many protection engines analyze each copied file in real time.So, if you're moving thousands of small files or large volumes of data, the CPU and internal disk can become overloaded while the antivirus scans them one by one.

As long as you are sure that the files are safe, you can temporarily disable real-time scanning To perform a large backup, and then reactivate it immediately afterward. It's not something to do lightly, but it can make a noticeable difference in transfer speed.

Power options also play a role, especially in laptops. In power-saving mode or when using battery power, Windows may limit the power supplied to USB ports. to extend battery life, which directly affects the performance of "power-hungry" external hard drives.

File systems: NTFS, exFAT, FAT32 and their impact on speed

The file system with which the external drive is formatted affects both compatibility and performance. In Windows, NTFS It usually offers the best speed and handling of large fileswhile other formats prioritize compatibility with older devices.

FAT32, although it is the most compatible with older televisions, consoles and devices, It has a 4GB file size limit and inferior performance in many scenarios.For transferring games, ISOs, or large 4K videos, it clearly falls short.

exFAT appears as an intermediate alternative: It allows large files, is compatible with various operating systems, and generally performs better than FAT32.However, in purely Windows environments, NTFS remains the most robust option.

If you have a USB drive or external hard drive formatted in FAT32 and notice that copies are slow, you can Convert it to NTFS or exFAT using the command-line tool to avoid having to forma tear from scratch (although it's always advisable to make a backup in case something goes wrong).

From the Command Prompt with administrator privileges, the conversion is performed with commands such as convert E: /fs:ntfs o convert E: /fs:exfat (replacing E: with your drive letter). If the command returns errors or the drive has problems, you may have to perform a full format from Explorer, after first moving your data to another temporary drive.

Background processes and internal bottlenecks

Your computer's power is not infinite, and Windows tends to take advantage of it. There are often background processes consuming CPU, RAM, or disk space. right when you start copying files, and that results in speeds that go up and down for no apparent reason.

Integrated tools such as Windows Defender, search indexers or cloud synchronizers They may be working silently and reducing the read/write capacity of the internal disk from which you copy or to which you write.

To detect these cases, the best thing to do is open the Task Manager with Ctrl + Shift + Esc and take a look at the CPU, memory, and disk tabs. If you want more detailed control, you can use utilities for View real-time RAM usage and detect processes that overload the system. If you see one or more processes at 90-100% usage just as the backup crashes, you've probably found the culprit.

In many cases you can temporarily halt non-critical heavy processes, such as scheduled antivirus scans or bulk synchronizations, to clear the way for the transfer you need to make at that moment.

Another classic bottleneck is the original hard drive itself. If you're reading about a full, fragmented, or aging mechanical HDDIt's normal for the speed to drop sharply from time to time. Defragmenting, freeing up space, or even better, migrating to an internal SSD can directly impact the speed of copying to external drives.

SSD-specific performance: TRIM, firmware, and free space

SSDs, both internal and external, have their own particularities. To maintain a sustained high speed, they need proper management of free space and already deleted blocks.This is achieved thanks to technologies like TRIM.

On modern Windows and macOS, TRIM is usually enabled by default on most compatible SSDsTherefore, the system informs the drive which data blocks can be reused after files are deleted. This prevents write speeds from slowing down over time due to an excess of "dirty" blocks.

It is also important Keep the unit's firmware updatedMany manufacturers (including major brands like SanDisk, Dell, and others) distribute specific tools for Windows that allow Check your SMART health, update firmware and perform performance tests.

Another good habit is avoid filling the SSD to the maximumMost recommendations place the ideal free space margin at around 10-15%. Having this buffer allows the internal controller to better manage data distribution and maintain write speeds closer to their nominal values.

Finally, it's advisable to minimize unnecessary writing, especially on laptops. Features like hibernation write the entire contents of RAM to the SSD every time you close the lid, which causes wear and tear and takes up space that may not be worth it if you don't actually use that function.

When is it normal for speed to decrease and when should you worry?

When copying files, not every decrease in speed is a bad sign. It is completely normal for a transfer to start at 100-300 MB/s and, after a few seconds, drop to a lower, stable value., such as 40-80 MB/s, depending on the type of drive and the size of the files.

That initial drop is usually due to the combination of the Windows write cache and the internal cache of the SSD or diskOnce the cache is full, the system stabilizes at the actual sustainable speed of the physical medium.

You should start to suspect when Speeds fluctuate very sharply or drop to zero bytes per second repeatedly, for no apparent reason, especially if the estimated copy time starts to skyrocket and the files seem to "get stuck".

In those cases, it is advisable to review all the points discussed: USB type, cable, drivers, antivirus, background processes, drive health, and file systemA failure in any of them can cause these frustrating oscillations.

It is also advisable Do not run many bulk copies at once from Windows ExplorerIf you fill the queue with several simultaneous processes, the system has to divide bandwidth and I/O operations among them all, which usually ends up being slower than doing them one by one.

Programs to copy files faster and with more control

Although Windows File Explorer does its job, It's not exactly the most efficient, nor the one that offers you the most information and control over transfers.That's why numerous utilities have appeared aimed at optimizing the copying and movement of files.

Tools such as TeraCopy, Ultracopier, Fast File Copy, Copy Handler, CopyMastro, or FastCopy They don't perform magic at the hardware level, but they do manage the operation queue better, allow pausing and resuming, and display detailed statistics. to detect bottlenecks.

Ultracopier opts for a very simple interface, quite similar to the standard Windows copy window, but It includes advanced options for handling errors, skipping problematic files, and maintaining an organized queue. without the user having to be constantly monitoring it.

FastCopy, very popular among advanced users, focuses on Maximize disk speed by minimizing head movements on the HDD and aggressively managing buffersIts appearance is spartan, but its performance usually far surpasses that of Explorer in large batches of files.

Alternatives when USB is not a viable option

There are situations in which, due to persistent errors, bottlenecks, or a lack of devices, You can't copy your data through an external drive with the speed or reliability you need.In these cases, it's advisable to have other options available.

The cloud is one of the most accessible solutions: Services like Google Drive, Dropbox, or OneDrive allow you to upload files and retrieve them from another computer.without having to rely on physical storage. However, you do need a good internet connection and sufficient storage space.

Another alternative is to take advantage of the Local area network (LAN) for sharing folders between computers on the same Wi-Fi or wired networkFor very large files, connecting via Ethernet cable and enabling file sharing in Windows is usually faster and more stable than any free cloud service.

In environments where you constantly work with a lot of data, you might be interested in opt directly for a quality external hard drive, preferably an SSD, with a USB-C or Thunderbolt connection, instead of cheap flash drives that get overloaded at the slightest touch.

And when it's something specific and urgent, you can always resort to Web services for transferring files with temporary links, such as WeTransfer or Send Anywhere, which allow you to send large files without having to create complicated accounts or install heavy programs.

Properly adjusting the Windows write cache, choosing the right USB port, maintaining the file system, and monitoring background processes, You can get your external hard drives to perform much closer to their real speed, avoiding the typical mid-copy stoppages and making moving tens of gigabytes a quick and, above all, predictable task..