If you keep .img backups of SD cards, a local drive is the fast option, but it is also a single point of failure. A fire, a theft, or a dropped drive can take every image with it. Cloud backup solves that problem, but .img files punish careless cloud choices: they are huge, they change rarely, and they are useless if you cannot download them quickly when a card fails. This comparison is for Pi owners and collectors who want an offsite copy of their card images.
Verdict up front: for a library of .img files, choose the service whose storage model fits large, rarely changed files, and compress images before you upload them. pCloud suits a file-sync and lifetime-style storage approach for a personal archive, while Backblaze suits continuous backup of a whole drive. Neither is a magic fix for the size problem: the file is still the full card size until you compress it.
Links to pCloud and Backblaze in this article are plain links, not affiliate links. No commission rate is claimed for either service in this article, because no rate has been confirmed for this site. Win32 Disk Imager itself is Windows-only, version 1.0.0 from 2017-03-08, and its Read output is the full device size with no compression — the core fact behind every number in this comparison.
The size problem, stated plainly
A 128 GB card makes a 128 GB .img file, a 64 GB card makes a 64 GB file, and a 32 GB card makes a 32 GB file, regardless of how much data is actually stored on the card. Five 128 GB card images therefore need 640 GB of cloud storage before compression. Compressing with 7-Zip, as covered in compressing an .img file with 7-Zip, often reduces that substantially when the card has much empty space, but you should plan storage for the uncompressed total and treat compression as a saving, not a guarantee. The backup workflow is covered in backing up an SD card to an .img file.
Comparison: pCloud versus Backblaze for .img files
| Feature | pCloud | Backblaze |
|---|---|---|
| Storage model | Cloud drive and sync folders; you choose what to store | Continuous backup of selected drives and folders |
| Best .img use | A personal archive library you manage by hand | A whole backup drive that changes as you add images |
| Large files | Upload the compressed .img as a file in your drive | Backs up the file as part of the drive backup set |
| Restore pattern | Download the specific image you need | Restore the file from the backup set |
| What to check before buying | Current storage plan size, upload limits, and file-size handling on the product page | Current plan terms, what is included, and restore options on the product page |
| Weakness for .img use | You manage the library yourself; no automatic versioning of the source drive | Less direct control over individual archive files than a drive folder |
Plain links for reference: pCloud and Backblaze. Again, these are plain links, not affiliate links, and this article makes no claim about commission rates for either service. Check the current plan details on each provider’s own site before buying, because storage plans and limits change.
What to avoid
- Uploading uncompressed images by default: you pay to store and to upload empty card space. Compress first, then upload, and keep the uncompressed copy locally until the upload is verified.
- Using cloud storage as the only copy: if the account is locked, the subscription lapses, or the download is slow, you have no fast restore. Keep a local drive as well, as covered in our backup drive guide.
- Backing up the live card while the Pi is writing to it: image a card when it is not in active use, or shut the Pi down first, so the image is consistent. A half-written image restores half-written data.
- Forgetting that restoring overwrites everything: Win32 Disk Imager Write overwrites the entire destination drive. Restoring a cloud-downloaded image to the wrong drive destroys that drive’s contents, so check the drive letter every time.
A practical setup
Keep a local backup drive for day-to-day restores, compress images before uploading, and upload the compressed archive to your chosen cloud service as the offsite copy. Name files clearly, with card, date, and project, and test a restore from the cloud copy at least once — a backup you have never restored is only a theory. You can get Win32 Disk Imager from our download page.
Frequently asked questions
Why are .img backups so large in the cloud?
Because Win32 Disk Imager Read output equals the full device size with no compression. A 128 GB card produces a 128 GB file, so cloud storage for .img archives is priced by full card size, not by how much data is actually on the card.
Should I compress .img files before uploading them?
Usually yes. Compressing with 7-Zip after creating the image often shrinks it substantially when much of the card is empty, which saves both upload time and cloud storage. Keep the compression guide steps handy and verify the archive before deleting the original.
Is cloud backup a replacement for a local backup drive?
No. Cloud backup is a second copy for disasters such as theft, fire, or a failed local drive. Keep a local backup drive for fast restores, and use the cloud as the offsite copy, not the only copy.