3 vac \- create a vac archive on Venti
30 creates an archival copy of Plan 9 file trees on Venti. It can be used
31 to build a simple backup system. One of the unusual properties of Venti is
32 that duplicate blocks are detected and coalesced. When
34 is used on a file tree that shares data with an existing archive, the consumption of
35 storage will be approximately equal to an incremental backup.
36 This reduction in storage consumption occurs transparently to the user.
38 As an optimization, the
42 options, described below, can be used to explicitly create an archive relative to an existing archive.
43 These options do not change the resulting archive generated by
45 but simply reduce the number of write operations to Venti.
49 is the hexadecimal representation of the Sha1 fingerprint of the root of the archive, in this format:
52 vac:64daefaecc4df4b5cb48a368b361ef56012a4f46
60 Specifies the block size that data will be broken into.
61 The units for the size can be specified by appending
63 to indicate kilobytes.
65 The size must be in the range
69 Reduce the number of blocks written to Venti by comparing the files to be stored with
70 the contents of an existing
76 Do not include the file or directory specified by
78 This option may be repeated multiple times.
85 or the standard output if no file is given.
88 Include standard input as one of the input files, storing it in the archive
93 The network address of the Venti server.
94 The default is taken from the environment variable
96 .\" If this variable does not exist, then the default is the
99 .\" which can be configured via
105 archives that are found while reading the input files. This option is
106 useful for building an archive from a collection of existing archives. Each archive is inserted
107 into the new archive as if it had been unpacked in the directory in which it was found. Multiple
108 archives can be unpacked in a single directory and the contents will be merged. To be detected, the
111 Note, an archive is inserted by simply copying the root fingerprint and does not require
112 the archive to be unpacked.
115 Increase the performance of the
117 option by detecting unchanged files based on a match of the files name and other meta data,
118 rather than examining the contents of the files.
121 Print out various statistics on standard error.
124 Produce more verbose output on standard error, including the name of the files added to the archive
125 and the vac archives that are expanded and merged.
129 Plan 9's \fIvacfs\fR(4) and \fIventi\fR(8)