Re: File system defragmentation. Something that can resume after stopping.

On 5/12/26 6:02 PM, Jack wrote:
> On 2026.05.12 18:45, Dale wrote:
>> 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.
> Why not just start it again?  It isn't going to defrag any files it
> already defragged, is it?  As long as interrupting it is safe, and
> doesn't ever leave a damaged file or file system, I can't think of any
> problems.
>
> Jack
>


Actually, it starts over with the first file and starts working its way 
through again.  At least that is what it did in the past.  It puts this 
in front of each file.  [1/162725]  It starts at file 1 and then works 
its way through until it has done each file.  As you can see, I have 
over 162,000 files.  Right now, it is on file 49,566.  It's been running 
since Saturday I think.  Basically, it rewrites each file from 1 to 
total number of files whether it is fragmented or not.  That's what it 
looks like to me at least.

I will say that, in the past, it seems it is faster on the second run at 
first because it doesn't actually move data as much for file it already 
finished but it still checks each file and it is going to take a while 
still.  It doesn't save much time since it still checks every file in 
sequence.  Once it gets to where it stopped on first run, it slows down 
again as it moves data more.

I'll be honest, whatever it is would either have to use something other 
than e4defrag or create a list in a file somewhere then figure out which 
file to do first and do them one at a time with e4defrag. I'd suspect, a 
completely different tool would be the best way.  I'm just not sure if 
anyone has even done this.  Most people most likely don't even check to 
see if their files are fragmented or not.  Given the cost of hard drives 
right now, I hope one of these drives doesn't go bad.  I have one 20TB 
and one 12TB or 14TB spare but that is it.  I try to keep a spare around 
just in case.

I'll be glad when the AI folks are done buying hard drives.  They have 
driven the cost of hard drives and other computer components through the 
roof.  Given the number of drives in my rig right now, I'm sitting on a 
small fortune.  ;-)

Dale

:-)  :-)