[SATLUG] EXT3 inner workings and stuff

[Samuel Leon]

I am curious if anyone here has a good grasp of the inner workings of 
the ext3 filesystem.  I am having trouble finding out exactly what 
"indirect inodes" are.

Lets take this scan of a 160gb partition:

*52745 inodes used (0.22%)
     4417 non-contiguous inodes (8.4%)
          # of inodes with ind/dind/tind blocks: 7970/2609/0
30466022 blocks used (64.93%)
        0 bad blocks
        1 large file

    50028 regular files
     2653 directories
        0 character device files
        0 block device files
        0 fifos
        0 links
      183 symbolic links (183 fast symbolic links)
        0 sockets
--------
    52864 files*

Does the "ind/dind/tind" stand for indirect, double indirect, and triple 
indirect?  And what exactly does this mean?  Also is there any way to 
determine the over all fragmentation level of an ext3 partition?  From 
what I have read "non-continuous" is not necessarily fragmentation.

Thanks,
Sam