RE: Logging ISP Download Speed.
Hi,
>>> Here my question is that, is it true that open two wget will affect
>>> the downloading speed? better one by one, just suspect it.
>>
>> Let's assume you have a 1.0 Mbit/s download connection. Because it
>> makes the math easier. And assume you need a 1.0 Mbyte file. With no
>> other overhead it will take aproximately 10 seconds to download.
>>
>> Now let's assume that you download two of those files at the same
>> time. You still only have 1.0Mbit/s download speed. But now you are
>> downloading 2.0Mbytes of data in total. Obviously the total download
>> will take aproximately 20 seconds to download.
>>
>> If you ran them sequentually then the first one would finish in 10
>> seconds and then the second one would start and it would finish 10
>> seconds later. So it would take 20 seconds in total for both to
>> download both of those files.
>>
>> If you ran them both at the same time then neither would be able to
>> get the full 1.0Mbit/s download speed. It should balance out between
>> them and each would get about 0.5Mbit/s download speed. Which would
>> double the amount of time each would take. Each would take about 20
>> seconds to download those files but both are running at the same time.
>> So once again it would take 20 seconds in total for both to download
>> those files. No difference!
One other thing to keep in mind. Usualy when downloading a file with a "chatty protocol", one that needs to confirm downloading a block to the server before the next block is sent, the actual filetransfer wil not fill the full bandwith, in those cases a second download will fill up that available bandwith. I see that a lot when I transfer files via my VPN connection from my Windows PC from/to the Windows server.
With a WAN optimized file protocol that is filling the available bandwith starting a second download at the same time will not help.
Bonno Bloksma
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