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I'm involved in a data warehousing project for which our clients need to be able to upload large files to our server. Our main concern is speed, since we're expecting to get several TB worth of data over a few months. Our server is on a VPN already, so our two options seem to be having our clients log into the VPN and transfer with (S)FTP, or set up a public-facing SFTP site.

Would one of these be significantly faster or easier? I don't know much about VPN, but one of my colleagues mentioned the possibility of the VPN timing out in the middle of the transfer, so could that be a problem? Are there any other problems I don't know about?

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closed as not constructive by Nifle, random Feb 16 '12 at 4:36

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up vote 5 down vote accepted

Neither FTP/VPN or SFTP is going to be faster than the other on large files. SFTP/VPN is going to encrypt twice, so will cost more resources - but is likely bandwidth constrained anyhow, so the extra CPU cost probably won't slow down the overall process.

Both SFTP and VPN have ways that they are easier: with SFTP, you have one tool to depend on, and direct visibility of every error in the sender. That makes it easier to debug, to diagnose problems, and to give good error reports.

On the other hand, a VPN means you can delegate the problem of "reliable security" to something other than your data transfer tool, so lower overhead if your requirements change, and perhaps a more robust transport if you use, eg, a well tested hardware solution.

Another possible difference is compression: SFTP can compress data in transit, so if your VPN does not that might help speed up the overall transfer ... or might not. If both compress, and you transport similar but distinct files, SFTP would lose state in the compressor that the VPN might retain, so you might see better results there - but I think it unlikely they would be statistically significant over the longer term.

I generally find simplicity to be the best choice, and one tool feels simpler to me unless you have an IT department that is going to take on all ownership of the VPN. You may weigh these factors differently.

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That all makes a lot of sense. I think we were leaning toward sticking with the VPN anyway, for the sake of not having to set up a whole new FTP site. Thanks! – andronikus Feb 15 '12 at 21:00

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