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cpddumbfs manual page


cpddumbfs [options] source target


cpddumbfs copy from and to an offline ddumbfs filesystem

One and only one of the source or target must be inside the ddfsroot directory.


-h, --help

show this help message and exit

-v, --verbose

display addresses and hashes from file (download only)

-l, --lock_index

lock index into memory (increase speed for large file)

-c, --check

check file integrity in exit code (download only)

-f, --force

download a file even if the header is corrupted or if bad blocks are found.



$ cpddumbfs -l /data/ddumbfs/ddfsroot/data /tmp
$ cpddumbfs /tmp/data /data/ddumbfs/ddfsroot


cpddumbfs is single threaded. If you have a multi-core CPU, cpddumbfs will be slower than copying files to the online filesystem. By default ddumbfs mount the filesystem with a pool of thread used to calculate block hash in parallel. When downloading file from the offline filesystem, cpddumbfs is as fast as the mounted filesystem.

See also

ddumbfs(1), mkddumbfs(8)


Alain Spineux <>