Transfer files from Backblaze B2 to Amazon S3
Server to server, without downloading anything to your computer.
How it works
Connect both accounts once. ShiftMyData then talks to Backblaze B2 and Amazon S3 directly and streams the files between them in memory — nothing is written to our disks, and nothing travels down to your machine and back up again. The job runs on a worker, so closing the tab does not stop it.
Will every file be verified?
Backblaze B2 offers SHA-1 and Amazon S3 offers MD5 — no checksum in common. Files are compared on size and modification time instead, which is the same basis every other tool uses for this pair; nobody can do better, because the two providers do not share a hash to compare.
Before you start
- The largest single file Amazon S3 accepts is 5 TB. A bigger one is reported as failed and the rest of the transfer carries on.
- Backblaze bills downloads beyond three times your average stored data in a month, so moving everything out at once can be billed by Backblaze.
- A transfer copies each file's current content, name and modification time; sharing and version history stay behind on Backblaze B2. Business migration carries them where both sides support them.
Sources: www.backblaze.com · www.backblaze.com · docs.aws.amazon.com · aws.amazon.com
Worth knowing about Backblaze B2
B2 charges nothing for uploads, and downloads are free up to three times what you store in a month, which makes it a cheap destination. Moving a whole archive back out in one month can pass that allowance, so check before you start.
Worth knowing about Amazon S3
S3 has no modification time of its own -- it records when an object was written, not when the file was authored, and that timestamp cannot be set. Transfers into S3 therefore compare on checksum where one is shared, and on size where one is not.
Steps
- On the Clouds screen, add Backblaze B2: paste an application key ID and key from the Backblaze console, ideally one limited to the bucket involved.
- Add Amazon S3 the same way: paste an access key ID and secret access key from the AWS console, ideally for an IAM user limited to the buckets involved.
- Pick the source bucket or prefix in the left pane and the destination bucket in the right.
- Choose a mode — copy, mirror, move, or two-way — and start the transfer.
- Leave it. Progress is on the Jobs screen, and a webhook can tell you when it ends.
Questions
Do I have to download my files from Backblaze B2 first?
No. The transfer is streamed from Backblaze B2 to Amazon S3 on our servers, so nothing is written to your machine and your home upload speed is not the limit.
What happens if I close my laptop?
The job keeps running. It is queued on a worker rather than in your browser, and the progress is there when you come back.
How do I know every file arrived?
Backblaze B2 offers SHA-1 and Amazon S3 offers MD5 — no checksum in common. Files are compared on size and modification time instead, which is the same basis every other tool uses for this pair; nobody can do better, because the two providers do not share a hash to compare.
Is there a size limit?
None imposed by us. What you move is drawn from your prepaid allowance (30 GB free, then 500 GB for ₹100 or 2,500 GB for ₹500, each valid a year). Amazon S3 takes single files up to 5 TB, and its own storage quota applies.