delta sync for big files?


just migrating from BT Sync to Syncthing.

Is that possible to update only big (200-200 GB) single files without syncing the whole file again?



I’m not 100% sure if i understood this right how it works but it should be like this:

  • append something -> only appended parts are transfered
  • replace something in the middle with something else that has the same length -> only changed part transfered
  • adding/deleting parts in the middle -> everything after the changed part transfered because all blocks after this will be different (probably also only the changes are transfered if exactly one block (128 KiB) of the file is added/removed, but I think it’s unlikely that this will happen)
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Alex is spot on. If your append in the middle/prepend was a multiple of 128kb, you’re still good.

Thanks, that was my question exactly!

It is great it works like this, so I can still sync/update only the difference in huge files.