Moving Individual LARGE files over wan


doesn’t come up often thankfully but wanted to revisit this topic

I am copying a 150 gig file over a very latent wan to a remote site with rclone, basically using either webdav/http serve on one end
tweaked vfs / buffer settings but the lack of multi-threaded uploads/downloads is limiting performance

(remote end is 50 megabit / 250 ms)

UPDATE I tried doing same with cache, my understanding from a previous post that that would allow for multiple download threads, that doesn’t seem to make a difference

just wondering if I missed anything obvious,
Plan B is probably upload to b2 or something comparable and download remote, might be a wash but wondering if anyone had any thoughts, thanks


I’m not following what you’re trying to do. Are you simply trying to copy one large file from site to site as quick as possible using rclone? What speed are you actually getting?


yes, getting maybe 20 megabit which with one TCP connection is exceptional
if I did multiple transfers of smaller files 50 megabit is no problem


I suspect it is that latency that is killing you. TCP is known to have a problem for high bandwidth + high latency connection (google “TCP Long Fat Pipe”)

Here is an article which suggests something like

Bytes in transfer = 50E6 / 8 * 250 / 1000 = 1562500

Rounding up to 1.5 MiB = 1572864

So you need to increase your receive and transmit windows to that number or bigger.

echo 1572864  > /proc/sys/net/core/wmem_max
echo 1572864 > /proc/sys/net/core/rmem_max

That should help a lot. You’ll need to do it at the source and destination.


this is actually

this is coming windows to windows which has their own rabbit hole related to this, but i will experiment, thanks