File system defragmentation. Something that can resume after stopping.

Howdy,

As most likely know, I have some fairly large storage systems here. I 
have one that while doing a fsck on, I noticed that it is really 
fragmented.  Something around 40% or so.  I'm running e4defrag on it but 
I suspect something will cause me to have to stop it before it 
finishes.  It has over 50TBs of data on it.  It's going to take a 
while.  I've looked at the man page and it has no resume option or many 
options at all really.  One to test, one to defrag is really it.  Rest 
is visual options like verbose.

I've googled around looking to see if someone came up with a script/tool 
or something that can defrag a file system and can resume if needed.  I 
can't find one.  Given e4defrag doesn't have good way to do it, I'm not 
surprised really.  The only thing I can come up with is to create a list 
of files that needs to be defraged, and then have a script that does 
them one by one until it is done. May require running more than once to 
really get the job done.

I have other file systems that are doing a lot better than this one but 
I also understand why this one is being fragmented so much. This file 
system receives files that are not complete but is being constantly 
written to until over time, it does complete.  This file system is on 
the receiving end of a disaster for keeping files in one long write.  
I'm sure ext4 is doing the best it can but it can only do so much.  I 
doubt any file system can do any better.

Does anyone know of a tool to use that has a resume option and works on 
ext4?  Obviously, I'd like it to be something that is well tested and 
known to be safe.  I'm just not having any luck finding one myself.  
Maybe one doesn't exist.

Thanks to all.

Dale

:-)  :-)