113 lines
2.2 KiB
Plaintext
113 lines
2.2 KiB
Plaintext
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.TH VENTI-BACKUP 8
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.SH NAME
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rdarena, wrarena \- copy arenas between venti servers
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.SH SYNOPSIS
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.PP
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.B venti/rdarena
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[
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.B -qv
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]
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.I arenapart
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.I arenaname
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.PP
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.B venti/wrarena
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[
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.B -o
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.I fileoffset
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]
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[
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.B -h
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.I host
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]
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.I arenafile
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[
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.I clumpoffset
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]
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.SH DESCRIPTION
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.PP
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.I Rdarena
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extracts the named
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.I arena
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from the arena partition
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.I arenapart
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and writes this arena to standard output.
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This command is typically used to back up an arena to external media.
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The
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.B -v
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option generates more verbose output on standard error;
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.B -q
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generates only errors on standard error.
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.PP
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.I Wrarena
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writes the blocks contained in the arena
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.I arenafile
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(typically, the output of
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.IR rdarena )
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to a Venti server.
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It is typically used to reinitialize a Venti server from backups of the arenas.
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For example,
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.IP
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.EX
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venti/rdarena /dev/sdC0/arenas arena.0 >external.media
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venti/wrarena -h venti2 external.media
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.EE
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.LP
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writes the blocks contained in
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.B arena.0
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to the Venti server
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.B venti2
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(typically not the one using
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.BR /dev/sdC0/arenas ).
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.PP
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The
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.B -o
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option specifies that the arena starts at byte
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.I fileoffset
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(default
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.BR 0 )
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in
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.I arenafile .
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This is useful for reading directly from
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the Venti arena partition:
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.IP
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.EX
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venti/wrarena -h venti2 -o 335872 /dev/sdC0/arenas
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.EE
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.LP
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(In this example, 335872 is the offset shown in the Venti
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server's index list (344064) minus one block (8192).
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You will need to substitute your own arena offsets
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and block size.)
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.PP
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Finally, the optional
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.I offset
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argument specifies that the writing should begin with the
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clump starting at
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.I offset
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within the arena.
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.I Wrarena
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prints the offset it stopped at (because there were no more data blocks).
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This could be used to incrementally back up a Venti server
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to another Venti server:
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.IP
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.EX
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last=`{cat last}
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venti/wrarena -h venti2 -o 335872 /dev/sdC0/arenas $last >output
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awk '/^end offset/ { print $3 }' offset >last
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.EE
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.LP
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Of course, one would need to add wrapper code to keep track
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of which arenas have been processed.
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See
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.B /sys/src/cmd/venti/words/backup.example
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for a version that does this.
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.SH SOURCE
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.B /sys/src/cmd/venti/srv
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.SH SEE ALSO
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.IR venti (6),
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.IR venti (8)
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.SH BUGS
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.I Wrarena
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can't read a pipe or network connection containing an arena;
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it needs a file already containing the entire arena.
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