term% cat index.txt VENTI-BACKUP(8) System Manager's Manual VENTI-BACKUP(8)
NAME
rdarena, wrarena - copy arenas between venti servers
SYNOPSIS
venti/rdarena [ -qv ] arenapart arenaname
venti/wrarena [ -o fileoffset ] [ -h host ] arenafile [ clumpoffset ]
DESCRIPTION
Rdarena extracts the named arena from the arena partition arenapart and
writes this arena to standard output. This command is typically used
to back up an arena to external media. The -v option generates more
verbose output on standard error; -q generates only errors on standard
error.
Wrarena writes the blocks contained in the arena arenafile (typically,
the output of rdarena) to a Venti server. It is typically used to
reinitialize a Venti server from backups of the arenas. For example,
venti/rdarena /dev/sdC0/arenas arena.0 >external.media
venti/wrarena -h venti2 external.media
writes the blocks contained in arena.0 to the Venti server venti2 (typ‐
ically not the one using /dev/sdC0/arenas).
The -o option specifies that the arena starts at byte fileoffset (de‐
fault 0) in arenafile . This is useful for reading directly from the
Venti arena partition:
venti/wrarena -h venti2 -o 335872 /dev/sdC0/arenas
(In this example, 335872 is the offset shown in the Venti server's in‐
dex list (344064) minus one block (8192). You will need to substitute
your own arena offsets and block size.)
Finally, the optional offset argument specifies that the writing should
begin with the clump starting at offset within the arena. 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:
last=`{cat last}
venti/wrarena -h venti2 -o 335872 /dev/sdC0/arenas $last >output
awk '/^end offset/ { print $3 }' offset >last
Of course, one would need to add wrapper code to keep track of which
arenas have been processed. See /sys/src/cmd/venti/words/backup.exam‐
ple for a version that does this.
SOURCE
/sys/src/cmd/venti/srv
SEE ALSO
venti(6), venti(8)
BUGS
Wrarena can't read a pipe or network connection containing an arena; it
needs a file already containing the entire arena.
VENTI-BACKUP(8)