Use multiple connections for single transfer not working :: Support Forum

nicknick
Joined:: 2018-01-20
Posts:: 3

Use multiple connections for single transfer not working

2018-01-20 00:26

No matter what I try, using multiple connections for a single transfer does not do anything.
I've turned off the "Preserve timestamp" option, checked the box "Use multiple connections for a single transfer", and set the maximum connection limit to 9.
The site I'm transferring files from uses SFTP.
Is this feature currently working with the SFTP protocol? Are there any other settings I should change to get this working?
Thanks,
-Nick

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martin◆ Site Admin
Joined:: 2002-12-10
Posts:: 41,415
Location:: Prague, Czechia

Re: use multiple connections for single transfer not working

2018-01-22

Please attach a full session log file showing the problem (using the latest version of WinSCP).

To generate the session log file, enable logging, log in to your server and do the operation and only the operation that causes the error. Submit the log with your post as an attachment. Note that passwords and passphrases not stored in the log. You may want to remove other data you consider sensitive though, such as host names, IP addresses, account names or file names (unless they are relevant to the problem). If you do not want to post the log publicly, you can mark the attachment as private.

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nicknick
Joined:: 2018-01-20
Posts:: 3

2018-01-24 04:20

See attached.
-Nick

nickserver.log (21.5 KB, Private file)

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martin◆ Site Admin
Joined:: 2002-12-10
Posts:: 41,415
Location:: Prague, Czechia

2018-01-25

OK, you have Calculate total size transfer options disabled
https://winscp.net/eng/docs/ui_transfer_custom
You have to enable it, if you want to use multiple connections for the transfer.
I have documented this constraint.
https://winscp.net/eng/docs/ui_pref_background

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nicknick
Joined:: 2018-01-20
Posts:: 3

2018-01-25 18:59

The transfer happens with one download thread even when I have the calculate file size enabled. I think there is something else going on here.

NickNick.log (19.26 KB)

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martin◆ Site Admin

2018-01-29

You are transferring a single file only. Did you expect WinSCP to upload chunks of the same file using multiple connections? WinSCP does not support that. WinSCP can only upload different files using parallel connections.

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alejandro Guest

2023-06-14 23:15

One solution I found is using 7-Zip to first split the file in chunks, ideally 9 chunks. If you don't want to compress you can set the compression level to "store", which will split the file super fast. This is also great because 7z has checksum when putting the file back together. Obviously this is only worth it for large files that take some time.

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martin◆ Site Admin

Re: Use multiple connections for single transfer not working

2023-06-15

This request is being tracked:
Issue 2205 – Upload single file using multiple S3 connections
You can vote for it there.

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Pueblo7230 Donor
Joined:: 2024-11-11
Posts:: 1
Location:: Australia

2024-11-11 03:44

I have been using the 7-zip hack to split large file and doing multiple parallel transfers. Thanks for raising the request to have this in the product. Do we have any estimate of when the request would be released or if it is on the roadmap?

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