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There is a pdf file Data.pdf (~10 MB) stored in my Google Drive folder. I open the file in Adobe Reader, highlight a line and then save the file.

A re-sync will take place. I want to know whether the entire 10 MB of file will be synced or there exists a way by which changes can be synced by uploading only a part of the file?

SubCollector Bhadrachalam
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2 Answers2

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The feature you are asking is called "Block-Level File Copying". With this feature, when you make a change to a file, rather than copying the entire file from your hard drive to the cloud server again, only the parts of the file that changed (called the delta) get sent.

A Google Drive sync cannot be partial. If a small change is made to a large file, it redoes the entire file rather than just the change. Google Drive isn’t capable of doing block-level file copies.

As far as I know, among the best-known cloud providers, only Dropbox has this feature for all file types. Dropbox partitions every single file it stores into 4MB blocks. Each block is hashed with SHA-256 and a list of these hashes gets stored in what’s called a “blocklist” for reference.

This feature is also shared by OneDrive, which however only supports it for Microsoft Office documents.

For more information and some benchmarks, see the article
Block-Level File Copying and the Cloud.

harrymc
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I realize this question is more than 6 years old, but thought it is worth updating the answer on this.

In January 2025 Google has "[..] added support for differential uploads to Google Drive, which means when large files are edited, Drive for desktop will now upload only the parts of the file that changed."

So while I haven't seen any tests of this implementation and I am not sure how fine grained the differential sync really is, it seems like this scenario should now be officially supported.

Source: https://workspaceupdates.googleblog.com/2025/01/release-notes-01-10-2025.html

marv51
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