Last summer when I was setting this up I could have swore I was getting these 512 errors.  Here is my config for my tar backup setup:

Note the small changes.   Good luck.  Check out the filelist.

# Local server backup of /etc as user backuppc
#
$Conf{XferMethod} = 'tar';

$Conf{TarShareName} = [
  '/'
];

$Conf{TarClientCmd} = '/usr/bin/env LC_ALL=C sudo $tarPath -c -v -f - -C $shareName --totals';

# remove extra shell escapes ($fileList+ etc.) that are
# needed for remote backups but may break local ones
$Conf{TarFullArgs} = '$fileList';
$Conf{TarIncrArgs} = '--newer=$incrDate $fileList';
$Conf{TarClientRestoreCmd} = '/usr/bin/env LC_ALL=C sudo $tarPath -x -p --numeric-owner --same-owner -v -f - -C $shareName+';

$Conf{IncrKeepCnt} = '10';
$Conf{BackupFilesExclude} = {
  '/' => [
    'gamma',
    'mnt',
    'proc',
    'media',
    'lost+found',
    'media',
    'sys'
  ]
};

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