1 be7cbb4e 2005-07-12 devnull .TH VENTI 1
  2 be7cbb4e 2005-07-12 devnull .SH NAME
  3 be7cbb4e 2005-07-12 devnull read, write, copy \- simple Venti clients
  4 be7cbb4e 2005-07-12 devnull .SH SYNOPSIS
  5 be7cbb4e 2005-07-12 devnull .B venti/read
  6 be7cbb4e 2005-07-12 devnull [
  7 be7cbb4e 2005-07-12 devnull .B -h
  8 be7cbb4e 2005-07-12 devnull .I host
  9 be7cbb4e 2005-07-12 devnull ]
 10 be7cbb4e 2005-07-12 devnull [
 11 be7cbb4e 2005-07-12 devnull .B -t
 12 be7cbb4e 2005-07-12 devnull .I type
 13 be7cbb4e 2005-07-12 devnull ]
 14 be7cbb4e 2005-07-12 devnull .I score
 15 be7cbb4e 2005-07-12 devnull .br
 16 be7cbb4e 2005-07-12 devnull .B venti/write
 17 be7cbb4e 2005-07-12 devnull [
 18 be7cbb4e 2005-07-12 devnull .B -z
 19 be7cbb4e 2005-07-12 devnull ]
 20 be7cbb4e 2005-07-12 devnull [
 21 be7cbb4e 2005-07-12 devnull .B -h
 22 be7cbb4e 2005-07-12 devnull .I host
 23 be7cbb4e 2005-07-12 devnull ]
 24 be7cbb4e 2005-07-12 devnull [
 25 be7cbb4e 2005-07-12 devnull .B -t
 26 be7cbb4e 2005-07-12 devnull .I type
 27 be7cbb4e 2005-07-12 devnull ]
 28 be7cbb4e 2005-07-12 devnull .br
 29 be7cbb4e 2005-07-12 devnull .B venti/copy
 30 be7cbb4e 2005-07-12 devnull [
 31 da0a205e 2009-08-21 extrudeda .B -fimrVv
 32 be7cbb4e 2005-07-12 devnull ]
 33 be7cbb4e 2005-07-12 devnull [
 34 be7cbb4e 2005-07-12 devnull .B -t
 35 be7cbb4e 2005-07-12 devnull .I type
 36 be7cbb4e 2005-07-12 devnull ]
 37 be7cbb4e 2005-07-12 devnull .I srchost
 38 be7cbb4e 2005-07-12 devnull .I dsthost
 39 be7cbb4e 2005-07-12 devnull .I score
 40 be7cbb4e 2005-07-12 devnull .SH DESCRIPTION
 41 be7cbb4e 2005-07-12 devnull Venti is a SHA1-addressed block storage server.
 42 be7cbb4e 2005-07-12 devnull See 
 43 d32deab1 2020-08-16 rsc .MR venti (7)
 44 be7cbb4e 2005-07-12 devnull for a full introduction.
 45 be7cbb4e 2005-07-12 devnull .PP
 46 be7cbb4e 2005-07-12 devnull .I Read
 47 be7cbb4e 2005-07-12 devnull reads a block with the given
 48 be7cbb4e 2005-07-12 devnull .I score
 49 be7cbb4e 2005-07-12 devnull and numeric
 50 be7cbb4e 2005-07-12 devnull .I type 
 51 be7cbb4e 2005-07-12 devnull from the server
 52 be7cbb4e 2005-07-12 devnull .I host
 53 be7cbb4e 2005-07-12 devnull and prints the block to standard output.
 54 be7cbb4e 2005-07-12 devnull If the
 55 be7cbb4e 2005-07-12 devnull .B -h
 56 be7cbb4e 2005-07-12 devnull option is omitted,
 57 be7cbb4e 2005-07-12 devnull .I read
 58 be7cbb4e 2005-07-12 devnull consults the environment variable
 59 be7cbb4e 2005-07-12 devnull .B $venti
 60 be7cbb4e 2005-07-12 devnull for the name of the Venti server.
 61 be7cbb4e 2005-07-12 devnull If the
 62 be7cbb4e 2005-07-12 devnull .B -t
 63 be7cbb4e 2005-07-12 devnull option is omitted,
 64 be7cbb4e 2005-07-12 devnull .I read
 65 be7cbb4e 2005-07-12 devnull will try each type, one at a time, until it finds
 66 be7cbb4e 2005-07-12 devnull one that works.
 67 be7cbb4e 2005-07-12 devnull It prints the corresponding
 68 be7cbb4e 2005-07-12 devnull .B read
 69 be7cbb4e 2005-07-12 devnull .B -t
 70 be7cbb4e 2005-07-12 devnull command to standard error
 71 be7cbb4e 2005-07-12 devnull to indicate the type of the block.
 72 be7cbb4e 2005-07-12 devnull .PP
 73 be7cbb4e 2005-07-12 devnull .I Write
 74 be7cbb4e 2005-07-12 devnull writes at most 56 kilobytes of data from standard input 
 75 be7cbb4e 2005-07-12 devnull to the server
 76 be7cbb4e 2005-07-12 devnull .I host
 77 be7cbb4e 2005-07-12 devnull and prints the resulting score to standard output.
 78 be7cbb4e 2005-07-12 devnull If the
 79 be7cbb4e 2005-07-12 devnull .B -t
 80 be7cbb4e 2005-07-12 devnull option is omitted,
 81 be7cbb4e 2005-07-12 devnull .I write
 82 be7cbb4e 2005-07-12 devnull uses type 0,
 83 be7cbb4e 2005-07-12 devnull denoting a data block.
 84 be7cbb4e 2005-07-12 devnull If the
 85 be7cbb4e 2005-07-12 devnull .B -z
 86 be7cbb4e 2005-07-12 devnull option is given,
 87 be7cbb4e 2005-07-12 devnull .I write
 88 3aec33fe 2005-07-18 devnull zero truncates the block before writing it to the server.
 89 be7cbb4e 2005-07-12 devnull .PP
 90 be7cbb4e 2005-07-12 devnull .I Copy
 91 be7cbb4e 2005-07-12 devnull expects
 92 be7cbb4e 2005-07-12 devnull .I score
 93 be7cbb4e 2005-07-12 devnull to be the score of a 
 94 be7cbb4e 2005-07-12 devnull .B VtRoot
 95 be7cbb4e 2005-07-12 devnull block.
 96 be7cbb4e 2005-07-12 devnull It copies the entire tree of blocks reachable from
 97 be7cbb4e 2005-07-12 devnull the root block from the server
 98 be7cbb4e 2005-07-12 devnull .I srchost
 99 be7cbb4e 2005-07-12 devnull to the server
100 be7cbb4e 2005-07-12 devnull .IR dsthost .
101 be7cbb4e 2005-07-12 devnull .PP
102 da0a205e 2009-08-21 extrudeda Venti's blocks are arranged in a directed acyclic graph (see venti(6)); 
103 da0a205e 2009-08-21 extrudeda there may be multiple paths from a root score to an 
104 da0a205e 2009-08-21 extrudeda interior block (for example, if the same file contents are stored
105 da0a205e 2009-08-21 extrudeda under multiple names in an archive).
106 da0a205e 2009-08-21 extrudeda .I Copy
107 da0a205e 2009-08-21 extrudeda runs more efficiently if it does not copy blocks 
108 da0a205e 2009-08-21 extrudeda (and all their children) multiple times.
109 be7cbb4e 2005-07-12 devnull The
110 be7cbb4e 2005-07-12 devnull .B -f
111 be7cbb4e 2005-07-12 devnull option causes
112 be7cbb4e 2005-07-12 devnull .I copy
113 da0a205e 2009-08-21 extrudeda to assume that if a block already exists on the destination
114 da0a205e 2009-08-21 extrudeda Venti server, all its children also exist and need not be considered.
115 da0a205e 2009-08-21 extrudeda The
116 da0a205e 2009-08-21 extrudeda .B -m
117 da0a205e 2009-08-21 extrudeda option causes
118 da0a205e 2009-08-21 extrudeda .I copy
119 da0a205e 2009-08-21 extrudeda to maintain an in-memory list of blocks it has copied
120 da0a205e 2009-08-21 extrudeda and avoid considering the same block multiple times.
121 da0a205e 2009-08-21 extrudeda The
122 da0a205e 2009-08-21 extrudeda .B -f
123 da0a205e 2009-08-21 extrudeda option is only useful if the destination Venti server is
124 da0a205e 2009-08-21 extrudeda known not to have lost any blocks due to disk corruption
125 da0a205e 2009-08-21 extrudeda or other failures.
126 da0a205e 2009-08-21 extrudeda The
127 da0a205e 2009-08-21 extrudeda .B -m
128 da0a205e 2009-08-21 extrudeda option is only useful if enough memory is available to
129 da0a205e 2009-08-21 extrudeda hold the block list, which typically requires about 1%
130 da0a205e 2009-08-21 extrudeda of the total number of bytes being copied.
131 be7cbb4e 2005-07-12 devnull .PP
132 be7cbb4e 2005-07-12 devnull The
133 be7cbb4e 2005-07-12 devnull .B -i
134 be7cbb4e 2005-07-12 devnull and
135 be7cbb4e 2005-07-12 devnull .B -r
136 a7f1ab29 2011-05-10 rsc options control
137 be7cbb4e 2005-07-12 devnull .IR copy 's
138 3aec33fe 2005-07-18 devnull reaction to errors reading
139 3aec33fe 2005-07-18 devnull from
140 3aec33fe 2005-07-18 devnull .IR srchost .
141 be7cbb4e 2005-07-12 devnull .I Copy
142 be7cbb4e 2005-07-12 devnull always prints information to standard error
143 be7cbb4e 2005-07-12 devnull about each read error.
144 be7cbb4e 2005-07-12 devnull By default,
145 be7cbb4e 2005-07-12 devnull .I copy
146 3aec33fe 2005-07-18 devnull exits after printing the first error.
147 be7cbb4e 2005-07-12 devnull If the
148 be7cbb4e 2005-07-12 devnull .B -i
149 be7cbb4e 2005-07-12 devnull option is given, read errors are ignored.
150 be7cbb4e 2005-07-12 devnull This is dangerous behavior because it breaks the 
151 be7cbb4e 2005-07-12 devnull assumption made by `fast' mode.
152 be7cbb4e 2005-07-12 devnull If the
153 be7cbb4e 2005-07-12 devnull .B -r
154 be7cbb4e 2005-07-12 devnull option is given, 
155 be7cbb4e 2005-07-12 devnull .I copy
156 be7cbb4e 2005-07-12 devnull replaces pointers to unreadable blocks with
157 be7cbb4e 2005-07-12 devnull pointers to the zero block.
158 be7cbb4e 2005-07-12 devnull It writes the new root score to standard output.
159 da0a205e 2009-08-21 extrudeda The
160 da0a205e 2009-08-21 extrudeda .B -v
161 da0a205e 2009-08-21 extrudeda option prints scores as it copies them, total writes, and other
162 da0a205e 2009-08-21 extrudeda debugging information.
163 da0a205e 2009-08-21 extrudeda The
164 da0a205e 2009-08-21 extrudeda .B -V
165 da0a205e 2009-08-21 extrudeda option prints debugging information about the Venti protocol
166 da0a205e 2009-08-21 extrudeda messages send/received.
167 be7cbb4e 2005-07-12 devnull .SH SOURCE
168 e5e159fd 2005-07-18 devnull .B \*9/src/cmd/venti
169 be7cbb4e 2005-07-12 devnull .SH SEE ALSO
170 d32deab1 2020-08-16 rsc .MR vac (1) ,
171 d32deab1 2020-08-16 rsc .MR venti (3) ,
172 d32deab1 2020-08-16 rsc .MR vacfs (4) ,
173 d32deab1 2020-08-16 rsc .MR venti (7) ,
174 d32deab1 2020-08-16 rsc .MR vbackup (8) ,
175 d32deab1 2020-08-16 rsc .MR venti (8) ,
176 d32deab1 2020-08-16 rsc .MR venti-fmt (8)
177 be7cbb4e 2005-07-12 devnull .SH BUGS
178 be7cbb4e 2005-07-12 devnull There should be programs to read and write
179 3aec33fe 2005-07-18 devnull venti files and directories.