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