November 29, 2025 by mguhlin

Rclone, anyone?

Every Thanksgiving break, I take a stab at backing up one of my external USB hard drives to another. It takes forever since the drives are huge and data is traveling over a USB connection. I’ve tried different solutions.

rclone on Zorin Core Linux in action (image excerpt)

Solution #1: FreeFileSync

This is a solution I have relied on and recommended to others. It works great on both Windows and GNU/Linux.

Image source: https://freefilesync.org/

Solution #2: TeraCopy

Another solution I’ve relied on is TeraCopy. It is easy to use and works well. That said, it’s not my go-to solution every time for USB external drive duplication.

And, finally, I recently found out about rclone. I wanted a command line option on GNU/Linux, hoping that it might get things done faster. I don’t know about faster, but ChatGPT recommended rsync first, then when I pushed it, ChatGPT coughed up rclone.

Solution #3: Rclone

This is the solution that’s working as I type this blog entry. It’s been working for over a day to clone one USB drive to another. ChatGPT points out the following:

Feature / Factor

rclone

FreeFileSync

TeraCopy

Platform

Windows, Linux, macOS

Windows only

GUI or CLI

CLI (scripts/automation), optional browser GUI

Full GUI

GUI

Speed: Large Files

Very fast; saturates disk

Very fast

Speed: Many Small Files

Fastest (parallel transfers)

Fast; faster than TeraCopy

Slowest

Directory Scanning Speed

Fast; tunable with --checkers

Fastest (multithreaded)

Slower

Incremental Sync

Best (smart sync)

Very good

Basic

Two-Way Sync

No (one-way, mirror, copy)

Yes (good for folder mirroring)

Integrity Checking

Strong (modtime, size, optional checksum)

Good

Minimal

Resume Support

Excellent

Good

Very good

Deletion Handling

Full sync/mirror options

Yes

Limited

Versioning

Yes (if used with backends)

Yes

Cloud Support

Extensive (70+ providers)

Partial

None

Scripting / Automation

Excellent

Weak

Real-time Sync

Via filesystem watchers

Built-in (RealTimeSync)

Best Use Case

Backups, automation, large datasets, mixed/complex jobs

Interactive folder sync, two-way sync, GUI workflows

Simple one-time file copies on Windows

Learning Curve

Medium

Low

Very low

Cost

Free

Speed Test

Scenario

Winner

Large files

Tie (all saturate USB/SSD speed)

Many small files

rclone, then FreeFileSync

Directory scan

FreeFileSync, then rclone

Repeated syncs

rclone

Simple drag-and-copy

TeraCopy

It went on to suggest:

Which tool should YOU use?

If you want fast, repeatable sync of two USB drives, the best choice is:
rclone (with parallel flags) rclone sync /src/ /dst/ --transfers=16 --checkers=16 --progress
If you want a visual “compare folders” interface and occasional sync:
FreeFileSync
If you want simple, reliable copying on Windows with pause/resume:
TeraCopy

Operating System Compatibility

I spend most of my time on GNU/Linux and Windows 11 these days, and had no idea rclone worked (or existed) on both. The commands are fairly similar:

Linux version

rclone sync /media/mg/USBDriveSource/ /media/mg/USBDriveTarget/ —transfers=16 —checkers=16 —progress

Windows version

rclone sync “SOURCE1” “SOURCE2” —transfers=4 —checkers=4 —progress

rclone copy “SOURCE1” “SOURCE2” —progress —update —transfers=4 —checkers=4

(Replace E: and F: with the actual drive letters.)

I’m looking forward to trying it out on Windows. But for now, the job is still running strong on Zorin Core Linux.

BiSync on Windows

Here is the clean starting-from-scratch bisync command using SOURCE1 and SOURCE2.

Because bisync needs an initial state, the first run must always include —resync.

First-time initialization (required once per pair):

rclone bisync "SOURCE1" "SOURCE2" --resync --progress --transfers=4 --checkers=4

This builds the bisync tracking files and establishes SOURCE1 and SOURCE2 as a synced pair.

All runs after the first initialization

rclone bisync "SOURCE1" "SOURCE2" --progress --transfers=4 --checkers=4

If something breaks and bisync asks to recover

Use —resync again:

rclone bisync "SOURCE1" "SOURCE2" --resync --progress

Reminder

Bisync is two-way: changes and deletions flow both directions.
If your intent is one-way without deletions, bisync is the wrong tool—use copy.