HOWTO : Segments

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HOWTO : Segments

Postby en_dator » 26 Jul 2009, 09:50

What to do if you want to use AirDC++ in hubs where other users or admins for some weird reason don't like segmented downloads.

First, tell them go suck something :mrgreen:
If that doesnt work, here is what you can do with your settings in AirDC++

Tab Settings / Queue
If your client has the option to Enable multi-source then set this to "Automatic" (this has nothing to do with segmented downloads anyway, but many people still confuse the two, and leaving it set to auto means it will not break anything else).

Manual settings of number of segments
Leave this unchecked unless you really really have to as if you set this to X, then every file you download, no matter what size will be split into X number of segments.

Enable segmented downloads
This you should check (If you think - now this guy is really stupid - I came here to find out how to disable segments and now he is telling me to ENABLE it. duh! - then just continue reading and I will tell you why).

Use antifragmentation method for downloads
Please have this checked as it can cause corrupted downloads if unchecked (this option is already removed in DC++ and I'm sure other clients will follow).

Tab Settings / AirDC++ / AirDownloads
Minimum segment size
Now here is where the magic happens, the size you set in this box is the smallest size a segment will be for all downloads that does not have its number of segment set manually.
You can set (almost) any size you like here, if for example you set it to 51200 ( 1024kB * 50 = 51200kb = 50mb) then files smaller than this will not be split, and files larger than this will be split into 50mb parts. DO NOT set silly huge values like 1TB or something like that, but keep it reasonable and everything should be fine.

There is also a setting on the Queue tab that sometimes makes a weird result, its called "Overlap slow chunks by faster user when file is going to be finished" and is normally enabled by default, if you notice that your client is "jumping" between two or more sources where they break eachother off and completing eachothers files, switching this off should help.

Setting up your client like this will mean you have all the benefits of multi-source but without the hassle of getting harassed by those that do not like segments.

Now, why should you have segments enabled even if you do not want to use them?
As you probably remember, in older clients there was something called rollback, this setting controlled how much of the already downloaded file the client should "cut off" at the end of the file when resuming a download, while this is a good practice when downloading something from beginning to end in one order, it has a less than ideal side effect. If your download is again interrupted the client will again cut off a part of the file and a second time try to request it. As you understand the result of this is that if there is a bad connection it can mean you are downloading much more than the actual file size, it can even mean your file will scrink instead of grow.

With new clients this is gone and instead there is something called TTH leaves, or chunks. A chunk is a part of the file as described by its checksum (the TTH stuff, if you want to know more about that there is an excellent post here : http://dcpp.wordpress.com/2006/03/09/ti ... ger-tiger/ and this is the smallest part that can be identified by the client. Using the full TTH hash each individual chunk can be verified and anything missing or corrupt can be redownloaded to create a perfect copy of the remote file totally eliminating the need for the old rollback mechanism.

There is also a bug that shows when segment function is disabled (this is in all clients based on DC++ and StrongDC++). The bug is supposed to be fixed and in next version of AirDC++ (2.06) the fix will be in AirDC++ too. The bug can cause corrupted downloads and the only way to avoid this is to have segment function enabled.



Links :
Why its better to use antifragmentation method for downloading:
http://dcpp.wordpress.com/2008/07/16/no ... downloads/
(anyone have more good links to connect here?? )
ÜndèrGrøund® Ñètwø®k - FlexHub - AirDC++
Because the world never was the same, and never will have been http://xkcd.com/394/
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Re: HOWTO : Segments

Postby irish » 28 Oct 2014, 01:19

Hello. I have the latest version of Air. Can you please tell me, where tab settings is?
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Re: HOWTO : Segments

Postby irish » 28 Oct 2014, 01:32

okay, ignore that, i was looking how to turn off segmented downloading. it was under "downloads" not "que"
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Re: HOWTO : Segmented downloads disable AirDC++ v 3.50

Postby goingdownsouth » 12 Jun 2018, 20:43

In the newest version of AirDC++ the segmented downloading can be disabled following :
File menu -> Downloads -> Settings (on top, left) -> OK :)
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