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0b8aa412 »
2010-09-21 merged virga1 and master
1 ==========
2 Lantorrent
3 ==========
4
5 Lantorrent is a file distribution protocol integrated into the Nimbus
6 IaaS toolkit. It works as a means to multi-cast virtual machine images
7 to many backend nodes. The protocol is optimized for propagating
8 virtual machine images (typically large files) from a central repository
9 across a LAN to many virtual machine monitor nodes.
10
11 Lantorrent works best for the following scenarios:
12
13 1) large file transfers (VM images are typically measured in gigabytes)
14 2) local area switched network (typical for data center computer racks)
15 3) file recipients are willing peers.
16 4) many endpoints request the same file at roughly the same time
17
18 -----------------
19 Protocol overview
20 -----------------
21
22 When an endpoint wants a file it submits a request to a central agent.
23 This agent aggregates request for files so that they can be sent out in
24 an efficient single multi-cast session. Each request for a source file
25 is stored until either N request on that file have been made or N'
26 seconds have passed since the last request on that source file has been
27 made. This allows for a user to request a single file in several
28 unrelated session yet still have the file transfered in an efficient
29 multi-cast session.
30
31 Once N requests for a given source file have been made or N' seconds
32 have passed the destination set for the source file is determined. A
33 chain of destination endpoints is formed such that each node receives
34 from and sends to one other node. The first node receives from the
35 repository and send to a peer node, that peer node sends to another,
36 and so on until all receive the file. In this way all links of the
37 switch are utilized to send directly to another endpoint in the switch.
38 This results in the most efficient transfer on a LAN switched network.
39
40 Often times in a IaaS system a single network endpoint (VMM) will want
41 multiple copies of the same file. Each file is booted as a virtual
42 machine and that virtual machine will make distinct changes to that file
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2011-03-04 Fix typo in README
43 as it runs, thus it needs its own copy of the file. However that file
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2010-09-21 merged virga1 and master
44 does not need to be transfered across the network more than once.
45 Lantorrent will send the file to each endpoint once and instruct that
46 endpoint to write it to multiple files if needed.
47
48 -----------------------------
49 Enabling Lantorrent in Nimbus
50 -----------------------------
51
aa6a4177 »
2010-10-30 Improve LANTorrent docs, and sync HTML and README
52 Lan torrent is part of the Nimbus distribution as of Nimbus 2.6.
53 However, due to system administrative overhead it is not enabled by
54 default. To enable Lantorrent in Nimbus there are a few configurations
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2010-09-21 merged virga1 and master
55 changes that must be made.
56
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2010-10-30 Improve LANTorrent docs, and sync HTML and README
57 The following software is required on both service and VMM nodes:
a0c4bcd9 »
2011-01-24 updating the doc the show a dependency on py 2.5. There is a problem …
58 - python 2.5
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2010-10-30 Improve LANTorrent docs, and sync HTML and README
59 - python simplejson
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2010-10-07 Add a note about dependencies
60
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2010-10-30 Improve LANTorrent docs, and sync HTML and README
61 Lantorrent is run out of xinetd thus it must also be installed on all VMMs.
62
63 To install LANTorrent you must take the following steps:
64
65 1) edit $NIMBUS_HOME/nimbus-setup.conf
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66 change lantorrent.enabled: False -> lantorrent.enabled: True
67
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2010-10-30 Improve LANTorrent docs, and sync HTML and README
68 2) edit $NIMBUS_HOME/services/etc/nimbus/workspace-service/other/common.conf
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2010-09-21 merged virga1 and master
69 change the value of propagate.extraargs:
70 propagate.extraargs=$NIMBUS_HOME/lantorrent/bin/lt-request
71
72 be sure to expand $NIMBUS_HOME to its full and actual path.
73
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74 3) install lantorrent on VMM
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2011-05-19 repackaging lantorrent to be more pythonic
75
76 - run: python setup-vmm.py install. This will output the contents of
77 the xinetd configuration file that you will need in the next step.
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2010-09-21 merged virga1 and master
78
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2010-10-30 Improve LANTorrent docs, and sync HTML and README
79 4) install lantorrent into xinetd
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2011-05-19 repackaging lantorrent to be more pythonic
80 - the above step outputs and xinetd file like this:
81
82 ============== START WITH THE NEXT LINE ==================
83 service lantorrent
84 {
85 type = UNLISTED
86 disable = no
87 socket_type = stream
88 protocol = tcp
89 user = bresnaha
90 wait = no
91 port = 2893
92 server = /home/bresnaha/lt1/bin/ltserver
93 }
94 =============== END WITH THE PREVIOUS LINE =================
95
96 note the 'user' value. We strongly recommend that it is not 'root'.
97 This user will be the owner of all received files (the nimbus user)
98
99 Copy the output to a file called /etc/xinetd.d/lantorrent. Once
100 this is done restart xinetd (/etc/init.d/xinetd restart).
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101
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2010-10-06 lantorrent patches so it will work with older versions of python
102 5) change the propagation method.
103 - edit the file:
104 $NIMBUS_HOME/services/etc/nimbus/workspace-service/other/authz-callout-ACTIVE.xml
105
106 and change:
107 <property name="repoScheme" value="scp" />
108 to:
109 <property name="repoScheme" value="lantorrent" />
110
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2010-10-30 Improve LANTorrent docs, and sync HTML and README
111 6) restart the service: $NIMBUS_HOME/bin/nimbusctl restart
112
113 7) [optional] if the path to Nimbus on the workspace control nodes (VMMs)
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2010-09-21 merged virga1 and master
114 is not /opt/nimbus you will also need to edit a configuration file on
115 all backends.
116
117 In the file:
118 <workspace control path>/control/etc/workspace-control/propagation.conf
119
120 make sure the value of:
121
122 lantorrentexe: /opt/nimbus/bin/ltclient.sh
123
3eb657a3 »
2010-10-10 Fix typo
124 points to the proper location of you ltclient.sh script. This should
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2010-09-21 merged virga1 and master
125 be a simple matter of changing /opt/nimbus to the path where you chose
126 to install workspace control.
127
128 ----------------
129 Protocol details
130 ----------------
131
132 requests
133 --------
134
135 transfer
136 --------
137
138 A transfer from one peer to another is performed for forming a TCP
139 connection. A json header is first sent down the socket describing the
140 transfer. It describes the files where data must be written, and the
141 other endpoints where the data must be sent. As data comes in the
142 server will store it to one or more files and forward it on to another
143 endpoint. All of this information is contained in the header. The
144 header has the following format:
145
146 {
147 host
148 port
149 length
150 requests = [ {filename, id, rename}, ]
151 destinations =
152 [ {
153 host
154 port
155 requests = [ { filename, id, rename } ]
156 block_size
157 }, ]
158 }
159
160 When the server forms a connection with the next endpoint it will form
161 another header by removing the first entry of the destination list and
162 using the values contained in it as root level values in the header
163 described above. If the destination list is empty then the server is the
164 last in the chain and no forwarding is needed.
165
166 After the header is sent the binary payload (the contents of the file)
167 is sent down the socket.
168
169 The 'requests' value of the json header contains destination
170 information. Each filename in the list is a file where data should be
171 written. The value of id is the id of the request for that file. The
172 value of rename is a boolean which determines if the file should be
173 first written to a temporary location and then moved to the final
174 location once all of the data is received. This feature is helpful in
175 monitoring file completion.
176
177 security
178 --------
179
180 Each connection to a lantorrent peer comes with a json header. Directly
181 following that header is a line of text in the following format:
182 EOH : <signature>
183
184 The value of signature is the hmac signature of everything that came
185 before the literal EOH. The password for that signature is found in the
186 lt.ini file. Every endpoint and the master repo must have the same
187 value for that password.
Something went wrong with that request. Please try again.