Re: [squid-users] Problems with Internet Download Manager and Squid 2.7 Stable 9

On 19.01.12 05:16, Saiful Alam wrote:
>I am using Squid 2.7 Stable on Ubuntu 10.10 x64
>
>Files like
> mp3 which have a refresh_pattern defined, and downloaded within the
>browser download manager is cached, but if I download the file with
>Internet Download Manager 6.05, the file is not cached. Note that IDM by
> default uses 8 connections to download a single file. Again, if I
>reduce the default connection number to 1, and try to download again
>with IDM, then the file is cached instantly.
>
>Most users in our
>network have IDM as their primary download manager, and if we can't
>cache objects downloaded with IDM, then :((((((((((((((((

I'm afraid this is due to suid not being to cache partial files at this
time. Other problem can be causes by current squid not able to do
collapsed forwarding (fetch the same file only once even when there's
multiple requests for that) which is related to this problem and afaik
in progress for 3.2.

Download manager that download multiple chunks in parallel encounter
this behaviour and often cause data not being cached.

You can configure squid to work around this behaviour by configuring
quick_abort_* values to fetch while files even if it's not requested in
hope that it will be requested later.

Problems are in cases like windows updates that are configured in large
files of which only small parts are needed, so you would fetch data not
needed (you can avoid this by having local WSUS server).

Other problems can be download managers fetching the same file from
multiple sources, but that's again problem with download managers.

Note that most download managers open multiple connections to get more
of bandwidth, which results in keeping less of the bandwidth to others.

That results in increased overhead (multiple connections, ack packets,
etc) and when more people use download managers, they only cause more
overhead flow through youur company's line.

I hope that any sane network admin configures networks so users can not
steal bandwitdh from others, only from themselves.

The most sane solution to this problem is configure download managers
to fetch each file only once.

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