This funny word
- 1 Availability
- 2 Choking
- 3 Data units
- 4 DHT
- 5 Downloader
- 6 Hash
- 7 ISP
- 8 Leech
- 9 Magnet Link
- 10 Multiple Hash Scrapes
- 11 NAT
- 12 P2P
- 13 Peer
- 14 Piece
- 15 Ports
- 16 Scrape
- 17 Seed
- 18 Seeding rank
- 19 Share ratio
- 20 Snubbing
- 21 SSL
- 22 Superseeding
- 23 Swarm
- 24 .torrent
- 25 Tracker
- 26 Unchoking
- 27 UPnP
Some useful definitions of funny BitTorrent words and terms
What does the Availability number tell you?
Availability is a per-torrent score like 0.640 or 37.989. The major number of the Availability tells you how many copies of the least available piece of the torrent you currently see. If the availability is 1 or more, you see all of the pieces of the file(s). If it is 0, you do not see the whole file(s). The decimals are most useful when the Availability is below 1. Lets say availability is 0.652, that means you're only seeing 65.2% of the file.
- Availability reflects your current view to the torrent. It changes constantly based on the seeds & peers you are connected to.
Availability has a direct impact on download speed too. If you are downloading a torrent with good availability, the speed is usually much higher than in a torrent with only one source (as that the upload speed of that source will then limit the whole swarm's download speed). You can also see in the example image that speeds of individual torrents can vary a lot.
You can (and should) easily enable the Availability column: just go to Library tab in Vuze (or the My Torrents tab in Azureus), right-click on the header row where the downloading torrents are queued and choose Column Setup. Enable the Availability column there and hit OK.
Another option to see the Availability is to open the torrent details via right-click > Show Details or doublecklicking on the torrent in the My Torrents view. The Availability is displayed there as a graphic bar and the Availability number itself on the right end of the bar.
Availability shown in the Library view:
- 0.000 means that the Tracker is offline or doesn't track this torrent anymore and DHT can't help either or there simply are no seeds left (old torrent).
- 0.249 means there are only parts of the torrent available (in this case 24.9%). Try to wait for seeds, you might have to wait a day or so. Or it is very new and in Superseeding mode
- 0.640 and all other peers stuck at nearly the same percentage (~64.0% in that case) means the torrent is either stuck because it lacks a seed or there is a very slow seed you're currently not connected to. Be patient, that torrent might finish, very slowly.
- 0.999 (or something below 1 near that) means there is almost 100% of the torrent available. This could be a anti-leech-protection, meaning you just have to wait a few hours or days for it to get 100% of it. If you are already trying to get it for 2 weeks or so read the Torrents stop at 99 percent page.
- 1.000 means that there is currently 100% of the torrent available. You are only able to download this torrent when the seed won't go offline before you got all of it.
- 1.539 and many peers stuck at ~53.9% (check the torrent details) means the swarm is either a bad torrent or the only seed is very slow and everybody is waiting for new data from him, thus you'll reach 53.9% very fast but the remaining 46.1% will take quite some time (could be hours or days) while the original uploader slowly uploads it to peers.
- 3.357 means there are some seeds and peers available and as you see at least 3 copies of each piece, you should be able to download the complete torrent, even if a seed stops seeding.
- 37.989 means that you are downloading a torrent with a big swarm. You see at least 37 copies of all data. If the Average Swarm Speed is not too low you should be able to download it rather fast (partly depending on your upload too).
Important things to note
Note that a good (high) Availability does not necessarily mean that it's a good torrent (and also read about Bad torrents). Another important thing is that seeds are NOT necessary to finish a download since peers can have data to share too, only an Availability above 1 (not counting cases with superseeds). That Availability > 1.0 condition can be also reached with several peers having different pieces of data, so that combined they have all the pieces.
Read the Azureus FAQ
- Choking: This is something that is part of the BitTorrent protocol, in the network. Choking is a signal that a peer is not intending to send you any data, until you are unchoked. This could be because the peer is not ready, or not willing to fulfill your requests. When you are connected to a peer, the connection contains information on 2 situations, one is choked or unchoked, the other is interested or not interested. Interested means, that peer has data that you do not have, and wish to acquire. New connections to peers always begin as choked and not interested. Peers will unchoke connected peers who upload fast but are not interested. If the fast uploading peers subsequently become interested, then the worst uploader gets choked. If you are interested in what the peer has, then that peer's client will calculate whether to send you the data, using information such as how fast you are uploading to other peers. When you are connected to many peers, you are never going to receive data from all of them at once. Sometimes data are sent to you from a particular peer, sometimes that peer sends to another peer instead, who may then upload to you. It is not possible for every peer to share data with every other connected peer at the same time. The TCP-Protocol used in BitTorrent to connect to other peers gets easily congested, and performs badly when sharing data over many connections at once. So choking is used to limit that congestion, and to help make sharing faster. Choking is also used to make sharing fairer to all, by ensuring that peers who upload more data faster to others get more data uploaded to them. So the more you upload, the more you can download from other peers. And the less you upload, the more likely you are to be choked. Also, read the info about unchoking.
- Bandwidth/Site Units: Confused about Kib/sec, KiB/sec, kB, kb and so on? Have a look at the Data units page.
- DHT: DHT is the acronym for 'Distributed Hash Table' and is the de-centralized tracking system used in Azureus 126.96.36.199 and later. The DHT has many uses, including but not limited to, finding peers while trackers are down, hosting completely trackerless torrents, and playing host to things like the 'Ratings and Comments' plug-in. You need to open the Incoming TCP port for TCP and UDP traffic to make it work. You'll then get a green dot with a user count at the bottom of the Azureus GUI, which should display about 400000 users or more. See http://en.wikipedia.org/wiki/Distributed_hash_table and http://en.wikipedia.org/wiki/Kademlia for further technical information.
- Downloader: a peer in a swarm who has not finished the whole torrent, or has not finished all the files that have not been marked as "Do Not Download". In BitTorrent, downloaders also upload to other peers, unless they are leeches. When a downloader completes the whole torrent, they become a seed and then only upload to other peers in the swarm.
- Hash: the hash is a string of gobbledegook characters in the .torrent file that the client uses to verify the data that is being transferred. It contains information like the file list, sizes, pieces, etc. Every piece received is first checked against the hash. If it fails verification, the data is discarded and requested again. The 'Hash Fails' field in the torrent General tab shows the number of these hash fails.
- Leech: an egoistic person who downloads a file using P2P technology, and who does NOT share (enough) with others when in possession of the complete file, reducing its Availability. Normally in BitTorrent, it is polite and considerate to leave your connection open long after you finish downloading to seed - so that other peers in the swarm, who do NOT yet have the complete file yet, benefit from you sharing, as you did benefit from others sharing when you originally downloaded the torrent. Some share more, some share less, but a leech is somebody who closes their connection as soon as they have downloaded the complete file. In the long run, your total Share ratio (Statistics -> Transfers Tab) should always be >1.000!
However, there is another interpretation of the term "leech" as being any user who has not completed the torrent download (ie anybody who has a percentage complete lower than 100% on a given torrent). Although Vuze chooses to refer to these users as "peers" in their client, there are official places (such as Demonoid) that still use "leech" in this manner.
Multiple Hash Scrapes
- Multiple Hash Scrapes: This is when, instead of Azureus scraping a tracker (from which you are running several torrents) separate times for each and every loaded torrent, Azureus can connect to that tracker one single time for all the loaded .torrents hosted on it. This is a tracker feature. This is a feature that is useful if you have more than one active .torrent which is hosted on the same tracker. Azureus can keep the connection to the tracker alive and do multiple scrapes during that single connection. This saves bandwidth, both for the tracker, and for you, since not so many connections need to be made. However, not all trackers support this feature. This is why, you may sometimes see a message in the tracker column in the "My Torrents" view, saying Multiple hash scrapes not supported. There is nothing you can do about this, nor is it something to get alarmed about. It simply means that Azureus will continue to scrape the tracker in the way it always has before, separate times for each torrent.
- NAT: This is short for Network Address Translation. This means that the Network, (which consists of any and all hardware you have connected up together, such as your router and your computer) needs to Translate the IP address of your router (which has it's own IP address) to and from the IP address of your computer (which also has it's own, different IP address). In simpler terms, it's sort of like mail forwarding. The router is there to help protect you from what it thinks is unwanted traffic, it is sort of like the Post Office. Inside the router, the port forwarding instructions are like telling the postman to redirect your mail to a different address. So the original address from the outside world (WAN, or Wider Area Network) is the IP address of your router, that's what the postman sees on the labels of parcels and letters. Then the postman redirects your mail according to the instructions you gave, to your ACTUAL address, which is the real local IP address of your computer, in the LAN (Local Area Network). See below for how to find out what the actual IP of your computer is on Mac OS X. So when you get the error message NAT Error, this means that your router is NOT translating the IP address from your computer to and from the outside world IP address of your router. And this is why no information or downloads can occur until this is sorted out, because information can not pass between your computer and the router, and thus cannot pass to and from the outside world of the internet. Please see NAT problem and PortForwarding for more information about this.
- P2P: is short for Peer to Peer, which is a technology to do with personal file sharing, which includes the like of BitTorrent, Gnutella, eDonkey, etc. Peer to Peer networks differ from other file-sharing networks in that there is no single centralized server.
- Peer: a person who is participating in file sharing. That is, a person who is transferring a file using P2P technology. Peers who have not already downloaded 100% of the torrent upload to other peers and download from them, while seeds just upload to other peers, improving their own Share ratio that way to prevent becoming a leech.
- Piece: every torrent is divided up into a bunch of small, equally sized pieces. These pieces are then transferred in a generally random order. Different pieces are sent to different peers so that each peer will have something the other peers do not, and the potential for trading is maximized to the fullest.
You normally have only one physical connection to a network at a time, but often use it for more than one thing, or logical connection, at a time. Ports are used to tell the operating system, which logical connection the received data packets are intended for.
For example, web browsing with Hyper Text Transfer Protocol (HTTP) usually uses port 80 while File Transfer Protocol (FTP) normally uses port 21. When you request a webpage, your computer sends a request packet to port 80 on the server, as it expects the web site's server to wait for your call at the default port. Port numbers run from 0 to 65535. Some of them are "reserved" for official purposes. You can go to http://ports.tantalo.net/ , the official IANA port list and http://en.wikipedia.org/wiki/List_of_well_known_ports_(computing) to find out more about which ports normally belong to which protocol/program.
The general advice is to use a randomly selected port between 49160-65534. Please read this article for more information on which ports to use with Azureus.
Originally bittorrent implementations (like Vuze/Azureus) used the port 6881, but as some ISPs started to block that port, Vuze currently recommends to use some other port and it randomly selects a port for a new installation. The selected port number itself does not change the functionality, as long as you configure your own network accordingly. Read all about port forwarding.
Information about ports that Vuze reserves by default.
Read the Azureus FAQ
- Seed: a peer who has 100% of the torrent and is only uploading to other peers. Seed is also used as a verb, as in "I'm going to be seeding this file overnight", meaning leave open and available for other users to download. Usually, a person with the whole file is a 'seed', while someone with a partial amount is a peer. Remember that a seed is not a file server. We're not talking about "magic seeds" here, so get any idea like that out of your mind. Connecting to more seeds does not necessarily mean that you'll finish downloading any faster. If you don't connect to all the seeds in a swarm, or even if you don't connect to any seeds, it does not mean Vuze is doing anything wrong. For any random torrent, you might download faster when connected only to 5 other peers and no seeds than you might with some other random torrent while connected to 50 seeds and no other peers. Seeding torrents improves your Share ratio.
- Seeding rank is a measurement of how urgent seeding of one torrent is against others. The higher the number, the more important it is for a given torrent to have more seeds, and the higher position it gets in the seeding queue. This is a useful metric for deciding when to terminate seeding activity for a particular torrent. Or just use the Ignore Rules to do that automatically.
See Share ratio
- Snubbing: This is something that any BitTorrent client does to a peer, when that peer tells you he will send you a requested block of data, but then fails to do so within a reasonable period of time (60 seconds for Azureus). Snubbing is a way to indicate that a peer is not trusted to fulfill requests for data. Whereas choking is done from the network, snubbing is done from the BitTorrent client. Snubbing happens when a peer promises to send data by unchoking us, but then does not send the promised and requested block within 1 minute. Usually Azureus makes multiple requests to any one peer, and queues them up, waiting for them to be fulfilled. When a peer is snubbed, only one request is queued to the snubbed peer at any one time. A peer is unsnubbed if they fulfill the one request they're given within 60 seconds. In some conditions, requests are not made from snubbed peers at all, such as when a torrent is almost complete and there are other unsnubbed peers available to make the requests from. The most likely reason for the offending peer is a misconfigured client. It may be uploading to too many peers without enough upload capacity.
- SSL: This is short for Secure Sockets Layer. This is a protocol developed by Netscape Communications. SSL makes it possible for encrypted, authenticated (i.e. by username and/or password) communication over the internet. It is possible to transmit private files this way. SSL is often used in communications between web browsers and web servers. For example, when you buy something over the internet, and you go to a secure page to enter your personal sensitive information such as credit card details, the URL beginning with "https" will indicate that this is an SSL connection. SSL is also used for people to securely access their home machines remotely when they are away from home.
- Superseeding: a feature that allows seeders who are the only seed in the swarm to solely seed pieces that are found nowhere else in the swarm. It works something like this: the superseeding client pretends not to be a seed, but pretends to be a peer with an incomplete file. Then the client shares each piece with one peer only. And that peer can then share that piece with the swarm. This allows the superseeding client to maximise the efficiency of the upload by only sharing those pieces nobody else has. And because of some other things about the behaviour of superseeding, this function does not work at all well in swarms with one peer and one seed only. So it is only good when the seeder is the only seed (usually the original uploader), and there are more than two peers. For more information please see Seeding Rules.
Note: Do not enable super-seeding for a torrent where you are not the only seed.
Read also: Super Seeding
- Swarm: the group of people, seeds and peers, who are active on a single torrent. It's perfectly normal NOT to connect to ALL seeds and peers in a swarm! A good Average Swarm Speed and Availability are more important. If you see something like 5 (14) in the seeds column it means that you are connected to 5 out of 14 seeds that are in the swarm - meaning that the tracker knows about 9 more seeds. If you see something like 12 (4) it could mean the tracker knows about 4 seeds in the swarm, but thanks to DHT you did connect to even more!
Please note that the total number of seeds and peers in the swarm is just the tracker server's current knowledge. It is no absolute truth. Some of the seeds/peers might already have closed their bittorrent clients and are thus no longer active. There is a defined time delay since last contact, after which the the tracker forgets about a seed/peer.
- .torrent: (aka. metafile) A .torrent file is a small text file that is used to start a torrent download. (A torrent is a set of data being shared.) The .torrent file contains information about the files included in the torrent, the address to the tracker server and error correction information.
- Tracker: a tracker is a special server that contains the information needed for peers to connect to other peers. Trackers coordinate the BitTorrent clients, and also keep track of statistics and verification information for each torrent. Azureus contains its own built-in tracker, but there are a variety of other tracker software packages in use. If the tracker server goes down and you try to start a torrent, you won't be able to connect to the swarm. Usually tracker errors are temporary, so Azureus will keep trying to scrape/connect again until successful or the torrent is removed. Please do NOT use the Manual Update button! The more you click it, the more this will destabilize the tracker, and cause it to go offline for everybody. So for the most part, leave the Manual Update button alone. Clicking it won't speed up your downloads, Good settings will.
- Unchoking is a promise to send data. Unchoking normally happens like this:
- When you are downloading, Azureus will unchoke to the optimal number of unchokes for your connection, in this order:
- The optimum uploaders (who upload at least 256B/s)
- Peers you are interested in (unless they are snubbed, or they have reached a Share ratio of 1/10, which means that every 1 byte they upload allows them to download 10 bytes)
- Peers who have globally uploaded you the maximum amount of data
- When you are seeding you will unchoke in this order:
- Peers who have uploaded the most the fastest
- Peers who have biggest portion of the file
- Here are some points to note about unchoking:
- When you are a seed, snubbed peers will never get unchoked
- Azureus will not snub any peer when you are seeding
- Manually snubbing someone can be done with a right (contextual) click on a selected peer in the details view
- This can let you have some control over which peers you do not want to send data to.
Read the Azureus FAQ