dcp

SYNOPSIS

dcp [OPTION] SRC DEST

DESCRIPTION

Parallel MPI application to recursively copy files and directories.

dcp is a file copy tool in the spirit of cp(1) that evenly distributes the work of scanning the directory tree, and copying file data across a large cluster without any centralized state. It is designed for copying files that are located on a distributed parallel file system, and it splits large file copies across multiple processes.

OPTIONS

-b, --blocksize SIZE

Set the I/O buffer to be SIZE bytes. Units like "MB" and "GB" may immediately follow the number without spaces (eg. 8MB). The default blocksize is 1MB.

-i, --input FILE

Read source list from FILE. FILE must be generated by another tool from the mpiFileUtils suite.

-k, --chunksize SIZE

Split large files into chunks of SIZE bytes to be processed. Multiple process ranks may copy a large file in parallel. Units like "MB" and "GB" can immediately follow the number without spaces (eg. 64MB). The default chunksize is 1MB.

-p, --preserve

Preserve permissions, group, timestamps, and extended attributes.

-s, --synchronous

Use synchronous read/write calls (open files with O_DIRECT). This also avoids caching the file data on the client nodes.

-S, --sparse

Create sparse files when possible.

--progress N

Print progress message to stdout approximately every N seconds. The number of seconds must be a non-negative integer. A value of 0 disables progress messages.

-v, --verbose

Run in verbose mode.

-q, --quiet

Run tool silently. No output is printed.

-h, --help

Print a brief message listing the dcp(1) options and usage.

RESTRICTIONS

If a long-running copy is interrupted, one should delete the partial copy and run dcp again from the beginning. One may use drm to quickly remove a partial copy of a large directory tree.

To ensure the copy is successful, one should run dcmp after dcp completes to verify the copy, especially if dcp was not run with the -s option.

EXAMPLES

1. To copy dir1 as dir2:

mpirun -np 128 dcp /source/dir1 /dest/dir2

2. To copy contents of dir1 into dir2:

mkdir /dest/dir2 mpirun -np 128 dcp /source/dir1/\* /dest/dir2

3. To copy while preserving permissions, group, timestamps, and attributes:

mpirun -np 128 dcp -p /source/dir1/ /dest/dir2

KNOWN BUGS

Using the -S option for sparse files does not work yet at LLNL. If you try to use it then dcp will default to a normal copy.

The maximum supported file name length for any file transferred is approximately 4068 characters. This may be less than the number of characters that your operating system supports.

SEE ALSO

The mpiFileUtils source code and all documentation may be downloaded from <https://github.com/hpc/mpifileutils>