Multiple connections to server in single WinSCP session.....

In uploading to my server on the west coast of the U.S. I typically see upstream speeds of 330 kB/s. My ISP provides me with an upstream bandwidth of 20+ mb/s. I like to be able to use more of the upstream pipe I have available to shorten file transfers.

If I have multiple files to transfer I can do so by opening multiple sessions of WinSCP and starting one (or several) transfers in each session. By doing that I see ~330 kB/s in each of the sessions, until I saturate my upstream pipe.

It would be great if WinSCP offered the option to connect X times to a server, thus allowing multiple files to transfer simultaneously.

jefe wrote:

It would be great if WinSCP offered the option to connect X times to a server, thus allowing multiple files to transfer simultaneously.

Well, it does. You can use up to nine background transfers.

Wow. Yes it does...and that works great!

Disregard my request for a feature that's already in place...and thank you for the heads up.

Is it possible to increase the limit of 9 simultaneous transfers? I have a high speed uplink, my target ftp server has a high speed inbound link. The limitation on transfer speeds is the latency across the net (from the West Coast to India). when I manually "execute now" more than 9, I see a significant improvement in utilized bandwidth. (I know that going too high will cause a drop in throughput... but 9 doesn't saturate any of the system or network resources involved.)

Thanks for the great work on winSCP!

steveinor wrote:

Is it possible to increase the limit of 9 simultaneous transfers? I have a high speed uplink, my target ftp server has a high speed inbound link. The limitation on transfer speeds is the latency across the net (from the West Coast to India). when I manually "execute now" more than 9, I see a significant improvement in utilized bandwidth. (I know that going too high will cause a drop in throughput... but 9 doesn't saturate any of the system or network resources involved.)

I 'm not sure if I want to allow users to make more than 10 connections to single server that easily. Moreover most FTP server wouldn't allow you anyway.

Well, in my case, it works fine on both the sending and receiving ends. This provides a huge improvement in throughput for me. It would be great to have this happen "automatically" based on the settings rather than forcing it to happen with a series of "execute now" steps on each transfer. I suspect that this is just a constant change in the code, right?

Thanks!

steveinor wrote:

I suspect that this is just a constant change in the code, right?

Right. Though I have just tried to set the limit higher. Unfortunately, WinSCP became instable then.

Thanks for checking into it, Martin.

martin wrote:

steveinor wrote:

I suspect that this is just a constant change in the code, right?

Right. Though I have just tried to set the limit higher. Unfortunately, WinSCP became instable then.

would it be possible to add an option somewhere that we could check or uncheck while downloading/uploading stuff from an SFTP/ftp server?

If we are allowed around 4 connections per file it should help a lot

Varun Raj wrote:

would it be possible to add an option somewhere that we could check or uncheck while downloading/uploading stuff from an SFTP/ftp server?

If we are allowed around 4 connections per file it should help a lot

This request has been added to tracker.

How to limit the maximum number of connections in C#?

Ashika wrote:

How to limit the maximum number of connections in C#?

WinSCP .NET assembly always uses one connection only. So what do you want to limit?

I am trying to open multiple sessions c# code, via threading. so parallel opening sessions for 10, winscp is throwing access denied even when it is 10 threads, means 10 sessions. Can you tell us how many sessions we can open in parallel? Because it is not letting even 10.

I am also getting
Exception: Server unexpectedly closed network connection.

Network error: Software caused connection abort
Authentication log (see session log for details):
Using username "SFTPUser".

The connection also getting aborted..
Please let us know how to over come this..

Ram wrote:

I am trying to open multiple sessions c# code, via threading. so parallel opening sessions for 10, winscp is throwing access denied even when it is 10 threads, means 10 sessions. Can you tell us how many sessions we can open in parallel? Because it is not letting even 10.

WinSCP does not have any limit. It's probably the server that limits the number of parallel sessions.

martin wrote:

Ram wrote:

I am trying to open multiple sessions c# code, via threading. so parallel opening sessions for 10, winscp is throwing access denied even when it is 10 threads, means 10 sessions. Can you tell us how many sessions we can open in parallel? Because it is not letting even 10.

WinSCP does not have any limit. It's probably the server that limits the number of parallel sessions.

Yes, could be server restriction. But i am using SSHD provided in winscp guide from git hub. How to solve the problem. Request you to guide us towards the solution.