Strange latency issue

[Levente Peres]

Dear All,

I've been testing Wanproxy for some time now.

The test environment is two CentOS 7 boxes, connected by separate 
OpenVPN capable routers. Clients behind the remote office WPX box 
connect to the local Samba server port 445.

[Clients]---[WPX]---[ROUTER]---((OpenVPN MTU 1400 UDP 
TUN))---[ROUTER]---[WPX]---[Samba]

Clients are not only transferring files, but prefer to work with their 
files online on the Samba.

When enabled, WPX provides for superior performance when using single, 
large, linear transfers. Compression, deduplication work as expected.

However when it comes down to "working remotely" with files, I have a 
big issue. Usually (I mean without using WPX) it takes for a user to 
"open" an xlsx file on the Samba, about 5-10 seconds on average. When 
using WPX, this is extremely increased, it can reach anything between 
1-2 minutes.

This behaviour reminds me of a time, when we had 1000+ pingtime on our 
WAN network (no we don't have it now) and they could go out and have a 
coffee while the XLS was being opened by Excel. I mean, it reminds me of 
Samba's behaviour when heavy latency is hitting it.

Not only that, but also, copying "sparese" files is very slow. The 
progress indicator stays on zero for seconds at a time, then quickly 
does the transfer and sits again for seconds.

All the while you can observe what I call "Samba chatter" going on back 
and forth.

Remove WPX and the problem is gone. Of course then the compression is 
gone too.

Want to emphasize again, once a transfer starts, it's very quick.

I tried playing with different parameters, like compression level, 
logging, statistics, debug... none of them made any difference regarding 
the latency problem.

If anyone could offer any insight into this I'd be very happy.

Thank you very much!

Levente