Something

{0}# createrepo -v -c /mirrors/apt/centos/4/en/i386/RPMS.rf/repodata_cache RPMS.rf
Directory must exist
{1}#     

{0}# ls -l RPMS.rf/repodata
total 3307
-rw-r--r--  1 root ftp 1516404 Mar 21 01:46 filelists.xml.gz
-rw-r--r--  1 root ftp  484340 Mar 21 01:46 other.xml.gz
-rw-r--r--  1 root ftp 1371804 Mar 21 01:46 primary.xml.gz
-rw-r--r--  1 root ftp     951 Mar 21 01:46 repomd.xml

{0}# ls -ld RPMS.rf/repodata_cache RPMS.rf/repodata
drwxr-sr-x  2 root ftp    176 Mar 21 01:46 RPMS.rf/repodata/
drwxr-sr-x  2 root ftp 285728 Mar 21 01:46 RPMS.rf/repodata_cache/

{0}# ls -l RPMS.rf/repodata_cache | wc
   3924   35309  366855

{0}#