Filesystem is full, but can't find space being used - Solaris

I saw a strange issue once where the  /staging filesystem is almost full, but I can't find where the space is being used. 

'df -h' command shows that the filesystem is 100% used as below.

==>df -h

Filesystem             size   used  avail capacity  Mounted on

/staging                 99G   99G   0K     100%      /staging

But 'du -h' command says that only 3.7G out of 99G is used.

==> pwd
/staging
==> du -h | grep "\.$"
3.7G .

This is strange , now how will you find which files are consuming remaining 95.3G of disk space. The unix command which can be used here is 'lsof' - list of open files.

==> lsof | grep -i /staging

cat        4723  user1 txt   VREG     270,28001          50028743680      15496 /staging (/dev/vx/dsk/staging)

cat        4723  user1 3r  VREG     270,28001          50028743680      15496 /staging (/dev/vx/dsk/staging)

sed        4724  user1 1w  VREG     270,28001          50028743680      15496 /staging (/dev/vx/dsk/staging)

ksh        8796   jg8789  cwd   VDIR     270,28001              1949696         11 /app/staging/pollers

ksh       10834  collect  cwd   VDIR     270,28001              1949696         11 /app/staging/pollers

cat       15794  user1  txt   VREG     270,28001          52067398891      36877 /staging (/dev/vx/dsk/staging)

cat       15794  user1 3r  VREG     270,28001          52067398891      36877 /staging (/dev/vx/dsk/staging)

sed       15795  user1 1w  VREG     270,28001          50028743680      15496 /staging (/dev/vx/dsk/staging)

All the highlighted entries sheds light on to the processes that are using huge disk space. Here we can see many 'cat', 'sed' commands are holding huge disk space which can be released by terminating the processes.

==> kill -9 4723  4724  15794  15795  

 DESCRIPTION ABOUT lsof 
    Lsof revision 4.82 lists on its standard output file infor-  
    mation about files opened by processes for the following  
    UNIX dialects:  
      AIX 5.3  
      Apple Darwin 9 (Mac OS X 10.5)  
      FreeBSD 4.9 for x86-based systems  
      FreeBSD 7.[012] and 8.0 for AMD64-based systems  
      Linux 2.1.72 and above for x86-based systems  
      Solaris 9 and 10  
    (See the DISTRIBUTION section of this manual page for infor-  
    mation on how to obtain the latest lsof revision.)  
    An open file may be a regular file, a directory, a block  
    special file, a character special file, an executing text  
    reference, a library, a stream or a network file (Internet  
    socket, NFS file or UNIX domain socket.) A specific file or  
    all the files in a file system may be selected by path.