Does iCloud compress and deduplicate (block level) stored files?

I have a lot of data (mostly documents, scanned images, etc.) that I want to store in iCloud by copying it to my Mac, and then (after it uploaded to iCloud) removing the local download to save storage space on my Mac. This way the same files will also be available from my iMac, MacBook, and iOS devices.


I currently have around 20TB of storage on various storage devices (NAS, local Servers, External drives, etc.) but I only have 2TB of iCloud Storage.


So the question is, will iCloud compress and do block level deduplication on the files stored in iCloud? Or will it store the duplicates as unique files? For example, say I store a 1GB PDF file in Documents/test/file.pdf, and I store an exact copy of the file under Documents/whatever/file.pdf - will iCloud only store the file once, and create 2 links to the file?


I have a lot of duplicate files from years of storing it on different devices (e.g. storing on an external drive, then storing the same data on a flash drive, and on my hard drive, and so on) that I need to organise. I will (at some point) sort these files out and organise them - and then only have a single copy. However, it will be very time consuming as it is hundreds of thousands of files stored in different folder structures.


I need to decide whether I just upload everything to iCloud and organise it later, or whether I need to organise it before uploading it to iCloud. if iCloud does compression and block level deduplication (in the same way that APFS, ZFS, or BTRFS does) the answer is simple - upload everything and organise it step-by-step. If not, the answer is simple - organise it first, then upload as the files are organised.

Posted on Aug 11, 2022 10:44 PM

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Posted on Aug 12, 2022 03:18 AM

I want to store in iCloud by copying it to my Mac, and then (after it uploaded to iCloud) removing the local download to save storage space on my Mac.


You will be disappointed. iCloud Drive does not work this way. It is a syncing service, unifying and updating the content between all you devices. If you edit, add or remove a file from your Mac the same action will be synchronised to all your other devices.


Read the following support documents

Set up iCloud Drive

Access and manage your files in iCloud Drive

Set up iCloud Drive on all your devices

Share files and folders in iCloud Drive on iCloud.com

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Question marked as Top-ranking reply

Aug 12, 2022 03:18 AM in response to Andre1357

I want to store in iCloud by copying it to my Mac, and then (after it uploaded to iCloud) removing the local download to save storage space on my Mac.


You will be disappointed. iCloud Drive does not work this way. It is a syncing service, unifying and updating the content between all you devices. If you edit, add or remove a file from your Mac the same action will be synchronised to all your other devices.


Read the following support documents

Set up iCloud Drive

Access and manage your files in iCloud Drive

Set up iCloud Drive on all your devices

Share files and folders in iCloud Drive on iCloud.com

Aug 12, 2022 04:29 PM in response to David McKinlay

I think we have a misunderstanding because I used the wrong terminology. Let me try again.


I want to upload the files to iCloud, and then use the "remove download" function to still keep the files stored in iCloud, but not physically stored on any of my devices. Although, the device will still have a link (shortcut) to the file that is stored online in iCloud. Please see below which feature I am referring to.






The little cloud icon is then displayed next to the file or folder name (of a file or folder that is stored online, but not locally) indicating that this file can be downloaded and accessed.




This would allow me to still access the data whenever I want - although the files will be downloaded every time I access it. The feature works great, I have been using it for some time, and it is saving me a lot of space on my devices. This is the very reason I started considering using iCloud for storage instead of a local NAS or server.


However, the original question (whether or not iCloud will compress and deduplicate the files I store online) remains unanswered.



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Does iCloud compress and deduplicate (block level) stored files?

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