High-Performance File Transfers Between AWS S3 and Cloudflare R2 via External Rclone on EC2

Modern teams often juggle multiple object-storage platforms and quickly discover that bandwidth, latency, and egress fees become critical roadblocks when large datasets travel through a local desktop. Running Rclone directly on a cloud instance—then controlling it through RcloneView—pushes the heavy traffic into the cloud’s high-speed backbone and keeps your laptop out of the data path.

The walkthrough below adapts the layout of the “Sync AWS S3 and Google Drive via EC2” guide and extends it to the S3 ↔ R2 scenario. You will:

1. Spin up Rclone as a remote-control daemon (rcd) on an AWS EC2 server.
2. Open a separate RcloneView window and connect to that external Rclone.
3. Add AWS S3 and Cloudflare R2 remotes inside the EC2-hosted Rclone.
4. Transfer, sync, or schedule jobs—entirely cloud-to-cloud—without local bandwidth constraints.

AWS Data-Transfer Fees

Intra-region traffic within the same Availability Zone is free, but cross-AZ and Internet egress incur costs (typically $0.02/GB AZ-to-AZ; $0.09/GB to the Internet). See: AWS Pricing – Data Transfer

Why Use an External Rclone?

Local Embedded Rclone	External Rclone on EC2
Traffic path: S3 → local PC → R2 — double hop and throttled by home upload speeds.	Traffic path: S3 → EC2 → R2 — single hop in the cloud’s backbone, often 10-25 Gbit/s.
Home ISP caps or asymmetrical bandwidth slow large migrations.	Vastly higher throughput; no local caps.
Local CPU and RAM must hash every byte.	Off-loads CPU to a cloud VM; you can pick larger instance sizes on demand.
Possible NAT/firewall issues.	Public IP with open port 5572 (or tunnel via SSH).

Part 1. Deploy Rclone on EC2 (External Rclone)

1. Launch an Ubuntu EC2 instance (t3.medium or larger for multi-threaded uploads).
2. Open TCP 5572 in the Security Group (or use an SSH tunnel).
3. Install Rclone:

curl https://rclone.org/install.sh | sudo bash

4. Run the rcd daemon with basic auth:

rclone rcd --rc-addr=0.0.0.0:5572 --rc-user=admin --rc-pass=admin --log-level INFO

The --rc-addr flag exposes HTTP endpoints for RcloneView to call.

5. Health-check from your laptop:

   curl -u admin:admin -X POST "http://<EC2-IP or DNS-NAME>:5572/rc/noop"

A JSON {} response confirms the daemon is listening.

👉 Learn more: How to Run Rclone on AWS EC2 Server

Part 2. Open a New RcloneView Window

To keep connections organized, RcloneView allows each window to operate with its own Rclone engine.

1. Launch RcloneView
2. Click the New Window button from the Home menu.
3. A new application window will open. This instance is independent of the main window and will maintain its own connection context.

📌 _You’ll connect this window to your External Rclone (EC2) in the next step..

👉 Learn more: Using Multiple Rclone Connections with New Window.

Part 3. Connect to the EC2-Hosted Rclone

In the newly opened window, follow these steps to connect to your EC2-hosted External Rclone:

1. In the new window, open Settings → Connection Manager.
2. Click New Connection and fill the form:

Field	Value
Display Name	ec2-rclone
Remote Address	http://<EC2-IP or DNS-NAME>:5572
Username	admin
Password	admin

4. Click Test Connection to verify the setup.
   You should see a successful connection response.
5. If the test passes, click Save, then **Connect.
6. You are now connected to your External Rclone instance running on EC2, and the connection status should appear at the top of the window.

Part 4. Add AWS S3 & Cloudflare R2 Remotes (via External Rclone)

➕ Add AWS S3 Remote

1. Go to the Remote tab, and click + New Remote.
2. In the Provider tab, choose Amazon S3.
3. In the Options tab:
   • Set provider to AWS
   • Enter your Access Key ID and Secret Access Key
   • Region and endpoint can be left default unless customized
4. Click Save to complete the setup.

👉 Learn more:

• How to Add S3 Remote
• How to get AWS S3 Access credential

➕ Add Cloudflare R2 Remote

1. Again, click + New Remote in the Remote tab.
2. In the Provider tab, select S3 (yes, again—R2 uses the S3 protocol).
3. In the Options tab:
   • Set provider to Cloudflare
   • Enter your Cloudflare R2 Access Key and Secret Key
   • Set endpoint to https://<accountid>.r2.cloudflarestorage.com
4. Click Save to complete the R2 remote setup.

👉 Learn more:

• How to Add S3 Remote
• How to get cloudflare R2 Access credential

Part 5. Sync Files Between AWS S3 and Cloudflare R2

🔁 Method A: Use Sync or Job

1. In the Explorer pane, select the Cloudflare R2 folder and the AWS S3 folder you want to synchronize.
2. Click the Sync button in the home menu.
3. Choose sync options (one-way or two-way), preview actions, and confirm.
4. RcloneView runs the sync and displays progress in the transfer log tab.

• For repeated or scheduled transfers:
  1. Click Save to Jobs in the Sync modal, or open Job Manager → Add Job.
  2. Configure source, destination, and options.
  3. Save and run manually or set a schedule.

👉 Learn more:

• Synchronize Remote Storages
• Create Sync Jobs
• Execute & Manage Jobs

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⏰ Method B: Schedule a Recurring Sync Job

1. In the Explorer pane, select the Cloudflare R2 and AWS S3 folders you want to keep in sync.
2. Open Job Manager from the Home or Remote menu, then click Add Job.
3. Confirm your source and destination.
4. Use the schedule editor to set when the job should run. Preview your schedule before saving.
5. Save and enable the scheduled job.

RcloneView will run the sync at your specified times. Check execution details and logs in Job History and receive notifications upon completion.

👉 Learn more: Job Scheduling and Execution

⚡ Performance Tuning Cheat-Sheet

Parameter	Recommended Value	Impact Level	Rationale
--s3-chunk-size	50M	*****	Larger parts reduce Class-A ops on R2 and improve speed1.
--s3-upload-concurrency	32–64	***	Increases multipart threads for R2.
--transfers	32–64	*	Parallel object uploads boost throughput on 10 Gbit links1.
--s3-disable-checksum	Add only when reconciling checksums externally	****	Skips per-part hashing bottleneck—use with caution1.

📈 Real‑World Tuning Results

To maximize performance during cloud-to-cloud transfers, we fine-tuned the Cloudflare R2 remote configuration as described below.

Experimental Results Only

RcloneView is a GUI frontend for Rclone. The performance tuning tips and benchmarks shared here are based on experimental testing inspired by community posts ( How to Maximize Multipart Upload Speed to Cloudflare R2) and may vary depending on your specific cloud environment, region, network conditions, and use case.

These results are not guaranteed and should be used as a reference only.

🔧 How to Update R2 Remote Settings

To change the configuration of the target R2 remote:

1. In the Explorer pane, click the gear icon next to your Cloudflare R2 remote, or go to Remote Manager → Edit.
2. In the Options tab, click Show advanced options.
3. Set the following values:
   • chunk_size = 50Mi
   • upload_concurrency = 32
4. Save your changes.

The disable_checksum option can also have a significant impact on transfer speed. However, for this test, we left it at the default value (false) to preserve integrity checks during file transfer.

📉 Baseline: Default Performance

When using default settings:

- chunk_size = 5Mi 
- upload_concurrency = 4. 

we observed transfer speeds of approximately 114 MB/s when moving large files from AWS S3 to Cloudflare R2 via EC2-hosted Rclone.

🚀 After Tuning: 4× Performance Boost

By updating the Cloudflare R2 remote with optimized settings:

- chunk_size = 50Mi 
- upload_concurrency = 32

and keeping disable_checksum = false, we achieved speeds of around 440 MB/s—a 4× improvement over the default.

✅ Summary

Cloud-to-cloud transfers no longer need to crawl through your laptop. By off-loading the heavy lifting to an external Rclone daemon on EC2, you unlock near-line-rate migration speeds, dodge AWS egress surprises, and keep your workflow fully visual inside RcloneView. Start your next S3 ↔ R2 move with confidence—and wave goodbye to local bottlenecks.

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🔗 Related Guides

• Storage Setup
  • How to Add S3-Compatible Remotes
  • How to Get AWS S3 Access Credentials
  • How to Get Cloudflare R2 Access Credentials
• EC2 & Remote Rclone
  • How to Run Rclone on AWS EC2
• Window & Connection Management
  • Using Multiple Rclone Connections with New Window
  • Manage Multiple RcloneView Windows
• Synchronization and Job Control
  • Synchronize Remote Storages
  • Create Sync Jobs
  • Execute & Manage Jobs
  • Job Scheduling and Execution
• Cost Considerations
  • AWS Pricing – Data Transfer
• Performance Optimization
  • How to Maximize Multipart Upload Speed to Cloudflare R2

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