Allow axel as a download agent

[GjjvdBurg]

Fixes #108. Allows using axel as a download agent, when this is available. The download agent can still be forced when needed.

[xdissent]

I've seen a few people request axel before, but I don't really see the benefit. All files are downloaded sequentially as they're needed, and that's just the nature of ievms, so the axel parallelism won't help anything. Additionally, curl is so ubiquitous it's nearly guaranteed to be installed already, reducing the dependency burden on the user. Am I missing something though? I appreciate the feedback regardless.

[GjjvdBurg]

The main advantage of axel is that it creates multiple connections to the
download server. This can provide a significant speed up, since a single
file is essentially downloaded in parallel. I agree that curl is
ubiquitous, that's why it is kept as fallback in the patch. Allowing axel
would therefore not introduce a dependency in my view.
On Jun 21, 2013 6:40 PM, "Greg Thornton" [email protected] wrote:

I've seen a few people request axel before, but I don't really see the
benefit. All files are downloaded sequentially as they're needed, and
that's just the nature of ievms, so the axel parallelism won't help
anything. Additionally, curl is so ubiquitous it's nearly guaranteed to be
installed already, reducing the dependency burden on the user. Am I missing
something though? I appreciate the feedback regardless.

—
Reply to this email directly or view it on GitHubhttps://github.com//pull/156#issuecomment-19826748
.

[xdissent]

But the modern.IE servers do not support Range requests, so axel can't actually download a single file in parallel.

[GjjvdBurg]

Perhaps there is some other way axel accelerates the download. I'm no
expert on how axel works, but in my small tests (screenshots attached)
there seems to be a difference in download speed. Although I do have to
admit that these tests are very far from scientifically sound, I think
they do show that there is a difference.

On 06/21/2013 08:18 PM, Greg Thornton wrote:

But the modern.IE servers do not support |Range| requests, so axel
can't actually download a single file in parallel.

—
Reply to this email directly or view it on GitHub
#156 (comment).

[rjmunro]

#162 is also dependent on the server supporting range requests, and comments there imply that the modern.IE server has been updated and now does support them.

Parallel downloading can provide a large speed increase to people with high latency connections.

Another option to provide parallel downloading would be to download the different VMs in parallel. This wouldn't require range requests on the server, but would be limited to people who wanted to install more than one VM.

[xdissent]

Thanks for the heads up - I'll reassess the resume capabilities soon.

[pjkix]

can we at least set up our own CDN / mirror that supports ranges and resumes since MS doesn't seem to care about this feature? downloading these files is very very painful :(