Syncing only modified chunks in big files?

[nice_furniture]

Do I get this right: I have a 10 Gbyte file and change it a bit so it is 11 GByte now. Does Btsync sync the whole file (11 GByte) or just the changed chunks (1 GByte)?

[Harold Feit]

If offsets change, you download the whole thing, if you only append and/or only change segments without changing offsets, you only get the changed chunks.

[nice_furniture]

Thanks! Ok, so I'm going to read on offsets and chunks. Any recommendation?

[nice_furniture]

Ok, I found this interesting thread: :

"Sync splits file to 4Mb chunks, if one chunk was changed - it will be transferred. It works well on files that doesn't change the size, for example TrueCrypt volume.

If you add one byte in front of the file, all chunks will be shifted and Sync will not be able to detect shifted data."

So it seems, Sync has to transfer the whole file all over someone adds something and so changes the file size.

[Harold Feit]

Specifically, only if the changes are early in the file. If they're late in the file or simply appending to the file, only the last chunk and any changed chunks would need to be (re-)downloaded

[nice_furniture]

Thanks for clarifying this.

[makapav]

Thanks!

On 5/29/2013 at 2:35 PM, nice_furniture said:

Ok, I found this interesting thread:

:

 

"Sync splits file to 4Mb chunks, if one chunk was changed - it will be transferred. It works well on files that doesn't change the size, for example TrueCrypt volume.

 

If you add one byte in front of the file, all chunks will be shifted and Sync will not be able to detect shifted data."

So it seems, Sync has to transfer the whole file all over someone adds something and so changes the file size.