[owncloud-devel] GSoC Proposal for Large File Sync

Klaas Freitag freitag at owncloud.com
Tue Mar 22 14:16:38 GMT 2016

On 21.03.2016 23:58, Tomaz Canabrava wrote:


> I can work on a proof of concept for large text files and virtual
> machine images (wich would already be a win-situation for some users)
> and then focus on *some* of the hard to sync files (like powerpoint
> presentations) and see what I could get.

I do not think you should consider the file type at all. Just try to
implement the zsync based approach I'd say, and just for the chunked 
upload mode.

Raw steps:
1. on the client, chop the file in chunks and create a list:

   Number of chunk     start-at-byte    end-of-byte   Checksum?

2. send this list to the server to get the servers checksums
3. While waiting on the server list of checksums, calc the client checksums
4. compare the lists once the both are ready and decide which need upload
5. upload the chunks that changed.

The trick is in the cutting of the chunks. The amount of chunks that do 
not change can be increased by picking clever boundaries.

This project requires both client and server work.

Please do the server work based on what is described in the blog series 
about the new chunking API, there is a branch with basic implementation 
of that here:

Makes sense?



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