Synology ds212j slow transfer speed

See: Robocopy /?

Usage : ROBOCOPY source destination [file [file]...] [options]

robocopy c:\folder d:\folder transfer_this.txt

Searching for "high latency file transfer" brings up a lot of interesting hits. Clearly, this is a problem that both the CompSci community and the commercial community has put thougth into.

A few commercial offerings that appear to fit the bill:

• FileCatalyst has products that can stream data over high-latency networks either using UDP or multiple TCP streams. They've got a lot of other features, too (on-the-fly compression, delta transfers, etc).

• The fasp file transfer "technology" from Aspera appears to fit the bill for what you're looking for, as well.

In the open-source world, the uftp project looks promising. You don't particularly need its multicast capabilities, but the basic idea of blasting out a file to receivers, receiving NAKs for missed blocks at the end of the transfer, and then blasting out the NAK'd blocks (lather, rinse, repeat) sounds like it would do what you need, since there's no ACK'ing (or NAK'ing) from the receiver until after the file transfer has completed once. Assuming the network is just latent, and not lossy, this might do what you need, too.