[plug] Mirrors

[Ben Jensz]

James Elliott wrote:

>How do mirrors work (not the glass ones but the ones we download from)?
>
>I gather the major downloads are not only stored on the source server but
>also on "mirrors" in other countries.
>
>1.  Since we pay no more for Internet use if we download from within
>Australia as distinct from overseas, why use mirrors? - what is the
>advantage?
>  
>
Well the end user pays no more anyway, it costs wholesale data carriers 
more for international traffic generally than domestic (Australian) traffic.

For users of ADSL in particular, most people in WA would be using a WAIX 
connected ISP and most are offering free data from WAIX connected 
servers, including some file mirrors.  So thats an advantage of using 
WAIX/Local ISP mirrors, as the data doesn't go towards your limit.

Also the closer the mirror (as long as its well connected), the faster 
sustained speeds you'll generally get from it also.

>2.  Who pays for the mirror sites if the downloads are free?
>  
>
Well the theory for the company that hosts the mirror, is if more than 
one of their users downloads the file from the mirror instead of from 
outside, then its data they are saving.  So instead of 5 users 
downloading the same 10Mb file each and using 50Mb of external 
bandwidth, the ISP or whoever the ISP sponsors to run the mirror 
downloads the 10Mb file once over the ISP's external bandwidth and the 5 
users download from that local mirror instead of from external.


/ Ben