How to set local file copy buffer size?

Question

Is there any sysctl parameter or any other mechanism to set or change file copy buffer sizes? I'm backing up a huge number of files to a local hard drive connected by firewire, and I'd like to play with file copy buffer sizes for the best performance. The machine used is a new macbook pro running OS-X 10.6.7. Any ideas?

Answer 1

Here is a bash script that uses the dd command to copy a file.  Use the -b option to set the file size.
example:
/Users/mac/config/forumcopy.command -vb  4096  /Applications\ \(Mac\ OS\ 9\)/Civilization\ II/Civ\ II\ Map\ Editor  /Applications\ \(Mac\ OS\ 9\)/Civilization\ II/Civ\ II\ Map\ Editorv8
I haven't tested this a lot. 
Of course, I haven't figured out how best to post code.  Trying HTML mode. Using the <pre> tag.
#!/bin/bash
# macteracopy [ -b blocksize ] [-v ] [-V ] input_file output_file
# Purpose of this script:
# Copy a file with optional block size. Default size of 4096.
# Notes:
# chmod u+x macteracopy
# You may have to restart the finder to notice a customized file icon.
#   Copyright 2010 rccharles
#   GNU General Public License
#   This program is free software: you can redistribute it and/or modify
#   it under the terms of the GNU General Public License as published by
#   the Free Software Foundation,  version 3
#   This program is distributed in the hope that it will be useful,
#   but WITHOUT ANY WARRANTY; without even the implied warranty of
#   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#   GNU General Public License for more details.
#   For a copy of the GNU General Public License see
#   <http://www.gnu.org/licenses/>.
# debug info
export PS4='+(${BASH_SOURCE}:${LINENO}):'
## not in the tiger version of bash ${FUNCNAME[0]:+${FUNCNAME[0]}(): }'
declare -x   verbose="No"   \
         veryVerbose="No"
blockSize=4096
# Check for command-line options used when calling the script
if [ $# -gt 0 ] ; then
   while getopts "b:vV" Option ; do
      case "${Option}" in
      b  )  blockSize=$OPTARG
      v ) verbose="Yes"
      V ) veryVerbose="Yes"
      \? ) echo 'usage macteracopy -b blocksize -V input_file output_file'
      * ) echo "Unknown argument among arguments $* on command line."
         exit 6
      esac
   done
fi
# We're done with switches / options from the command line
shift $(($OPTIND - 1))
[ "${veryVerbose}" = "Yes" ] \
   && set -x  
inputFile="${1}"
outputFile="${2}"
[ "${verbose}" = "Yes" ] \
   && echo \
   && echo "$0 script revised $(GetFileInfo -m $0)" \
   && echo
[ ! -f "${inputFile}" ] && echo "File not found.  ${inputFile}" && exit 4
[ -d "${inputFile}" ] \
   && echo "Directories are not supported, yet.  ${inputFile}" \
   && exit 4
[ "${veryVerbose}" = "Yes" ] \
   && ulimit -a \
   && df \
   && echo
if [ "${verbose}" = "Yes" ] ; then
   dd bs=${blockSize} if="${inputFile}" of="${outputFile}"
     dd bs=${blockSize} if="${inputFile}/rsrc" of="${outputFile}/rsrc" 
else
      dd bs=${blockSize} if="${inputFile}" of="${outputFile}"
      dd bs=${blockSize} if="${inputFile}/rsrc" of="${outputFile}/rsrc"
    } 2>/dev/null
fi
[ "${verbose}" = "Yes" ] \
   && echo \
   && ls -l "${inputFile}" \
   && ls -l "${inputFile}"/rsrc \
   && GetFileInfo  "${inputFile}" \
   && ls -l "${outputFile}" \
   && ls -l "${outputFile}"/rsrc \
   && GetFileInfo  "${outputFile}" \
   && echo
SetFile  -a $(GetFileInfo  -a "${inputFile}"  ) \
       -c $(GetFileInfo  -c "${inputFile}" | sed 's/"// g' ) \
         -t $(GetFileInfo  -t "${inputFile}" | sed 's/"// g' ) \
         "${outputFile}"
[ "${verbose}" = "Yes" ] \
   && echo "after SetFile" \
   && GetFileInfo  "${outputFile}"