Puppy Linux Discussion Forum

Hi all

Recently, I downloaded a Delta update for @ozsouth Fossapup23 and thought that could we not use Zsync to manage this. Also, @peebee kindly provides updates too in this manner.

How Zsync Works?

Zsync works by efficiently downloading and updating files by only fetching the parts of the file that have changed or are missing, rather than downloading the entire file from scratch.

Here's a more detailed explanation of how Zsync works:

Original File: Zsync starts with an original file that you want to download or update. This original file is typically hosted on a server.

Zsync File: Alongside the original file, a Zsync control file is provided. This file has the same name as the original file but with a ".zsync" extension (e.g., originalfile.iso.zsync). The Zsync control file contains metadata and checksum information.

Local Copy: You also have a local copy of the original file on your computer. This local copy might be an older version of the file that you want to update.

Zsync Algorithm: Zsync uses a specialized algorithm to compare the local copy of the file with the original file. It does this by comparing checksums and metadata in the Zsync control file.

Determining Differences: Zsync identifies the parts of the original file that are missing or have changed since your local copy was last updated. It does this without downloading the entire file.

Partial Downloads: Zsync then downloads only the specific parts of the original file that are missing or changed. These parts are referred to as "chunks."

Combining Chunks: Zsync combines the downloaded chunks with your local copy to create an updated version of the original file.

Checksum Verification: Zsync uses checksums and hash functions to verify the integrity of the downloaded chunks, ensuring that they match the expected data.

Final Updated File: Once all necessary chunks are downloaded and integrated into your local copy, you have the fully updated and correct version of the original file.

Zsync Benefits

The benefits of using Zsync are listed below:

Reduced Bandwidth Usage: You save on bandwidth because you're only downloading the portions of the file that have changed, which is much smaller than the entire file.

Faster Downloads: Since you're downloading less data, the process is generally faster, especially when updating large files.

Efficiency: Zsync is especially useful for downloading large files like Linux distribution ISOs or software updates, as it minimizes the time and resources required.

Checksum Verification: Zsync uses checksums to ensure the integrity of the downloaded parts, providing a level of data integrity verification.

That will be extremely useful if it works well. Of course rolling release type distros update so drastically and quickly, zsync may not provide much advantage. Pseudo full install type usage with reliable package manager is the optimum update mechanism maybe when huge changes are involved. Worth testing zsync anyway though and especially with some of the more static Puppy distro releases, so depends...

@wiak

It's straightforward to implement and ideally used by hosts eg @rockedge

The binary was compiled for FP95.