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I'm looking for a tool that can give me a visual representation of my ext4 fragmentation. Something similar to how Defraggler, Puran Defrag, and many others (UltraDefrag being the best) display your disk... (most good UIs display the files in the block you're hovering your mouse over)

Is there anything related for Linux?

I want to watch my disk and see just how "unneeded" defragmentation really is.

I don't want to use e4defrag, because I'm not sure it can show me what exactly it's doing to my disk.

EDIT (2021): it would seem a similar, less popular, question has been asked 3 years before this question with suggested tools: https://unix.stackexchange.com/questions/30743/is-there-a-tool-to-visualize-a-filesystem-allocation-map-on-linux

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    There is absolutely no need to defrag a linux machine.
    – ZaxLofful
    Sep 16, 2015 at 21:12
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    That is nonsense. The "need" of defragmentation depends on the FS type and usage pattern. In some cases defragmentation makes a huge difference. (I guess this is one of the linux myths) Sep 16, 2015 at 22:05
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    @DavidBalažic - reference please ? I see no need to defragment a a disk / file system with 0.2 % fragmentation. Please provide benchmarks to show defragmenting a ext2/3/4 / XFS / or any linux native file system significantly affects performance.
    – Panther
    Sep 17, 2015 at 15:19
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    @bodhi.zazen --> "depends on the FS type and usage pattern". In some cases it has a big effect, in others none. If that 0.2% is a 2GB database file that is in heavy use, then it will have a big effect. It is a few small rarely used files, then of course not. Sep 17, 2015 at 16:03
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    @DavidBalažic- Define "big effect" and post benchmarks. The i/o of the disk is going to hundreds of times more limiting then a small amount of fragmentation, it will take you a long time to write a 2 GB database to the disk and writing a part of a 2 Gb file is not going to be affected by 0.2% fragmentation, still have to re-write the data to disk. Any modern databse that is in heavy use will be in RAM and if you are writing to disk the limiting factor is RAM, not fragmentation.
    – Panther
    Sep 17, 2015 at 16:31

6 Answers 6

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The question is not if there is fragmentation. All file systems have some fragmentation.

The question is if the fragmentation is enough to affect performance.

On Linux file systems, fragmentation is typically less then 5%, often 1 or 2% unless the disk is 99% full. In the event of a full disk, you can see significant fragmentation, but in that case the problem is a full disk.

$ sudo fsck.ext2 -fn /dev/sda1
e2fsck 1.42 (29-Nov-2011)
Pass 1: Checking inodes, blocks, and sizes
Pass 2: Checking directory structure
Pass 3: Checking directory connectivity
Pass 4: Checking reference counts
Pass 5: Checking group summary information
Ubuntu_Rescue: 291595/1222992 files (**0.2% non-contiguous**), 1927790/4882432 blocks

So yes, there is 0.2 % fragmentation, but this is well below the 85% threshold to affect performance.

See the blog post Why doesn't Linux need defragmenting?.

On Windows, it is not uncommon to see 50% or higher rates of fragmentation (I have seen 200% plus). Thus windows needs defragmentation tools.

On Windows they advise defragmentation at thresholds of about 85%.

See:

So, bottom line, defragmentation is not a large enough problem on Linux to affect performance, so there are no significant defragmentation tools and you are sort of wasting your time worrying about it.

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  • well I've got time to waste to clear up another issue regarding this, so thanks, also, it's always good to be a skeptic ;)
    – Tcll
    Sep 16, 2015 at 15:55
  • I'm intrigued: what is meant by fragmentation of > 100%? Files are fragmented multiple times?
    – Doddy
    Sep 17, 2015 at 11:46
  • @doddy apparently so, or the fragments are fragmented. I am not familiar enough with either windows or NTFS to know how the fragmentation is measured .
    – Panther
    Sep 17, 2015 at 15:15
  • FWIW - Just today (been running this system with upgrades from Fedora 18 -> several updates -> now Fedora 22 ) fsck.ext2 -fn /dev/mapper/fedora-root /dev/mapper/fedora-root: 525176/3276800 files (0.6% non-contiguous) and /dev/mapper/fedora-home: 149180/11149312 files (1.1% non-contiguous) so not much fragmentation over years and several upgrades
    – Panther
    Oct 9, 2015 at 21:24
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    @Tcll I totally agree you should use Ext or similarly behaving FSs for Linux itself and it doesn't make much sense why it wouldn't be so - that however does not in any way affect the real other disks & partitions you have to deal with which originate from e.g. Windows and other OSs or have heavy I/O at nearly full capacities. I won't go futher here, but I think we are on the same page :)
    – jave.web
    Apr 20, 2020 at 11:25
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Let's keep it simple...

1) If you use EXT4, there is no need to defrag unless your disk is ~90% full and under heavy IO (Delete, Read, Write).

2) If you find yourself with a ~90% full disk that is heavily fragmented, then your problem is (IMHO) insufficient disk space and not fragmentation. Get a larger disk!

3) If you can't get a larger disk for any valid reason, then simply copy the whole lot (or by large chunks) to another disk, then copy it back. The advanced EXT4 FS writes it back contiguously eliminating fragmentation. This can be scheduled as a cron.daily job using Gnome Scheduler for the converts coming from Windows.

BEST FIX if you have the problem from point 2 above, get a larger disk!

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  • I would still like to watch the fragmentation and take care of things when it does happen (not through the terminal like most spud-head developers prefer) ;)
    – Tcll
    Sep 17, 2015 at 13:48
  • hence why I said use Gnome Scheduler for the "copy away and back pattern" Sep 17, 2015 at 23:08
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    @DanglingPointer what about those NTFSs though.... hmmm ? :) or a heavy I/O? hmmm ? :) people who simply don!t or can't afford "another disk" hmmm ? :)
    – jave.web
    Apr 17, 2020 at 11:47
  • @jave.web use btrfs with autodefrag mount option in fstab and never worry about defrag again. Oct 31, 2021 at 4:45
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    I can't eat apples if I only have oranges. People have NTFSs from win with no place nor time nor money to pour them through to another disk.
    – jave.web
    Nov 1, 2021 at 17:08
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There is no need for defragmentation on Linux systems.
So that is why there are not many defrag tools available.

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    I'm not convinced, show me the fragmentation of a full ext4 HDD after 2 weeks of use with constant deletion and addition of files, there's bound to be fragmentation.
    – Tcll
    Sep 16, 2015 at 15:21
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    There are many explanations online - one of them explains it quite precise : howtogeek.com/115229/…
    – cl-netbox
    Sep 16, 2015 at 15:31
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    I posted the documentation you requested , 0.2 % fragmentation is trivial and not enough to affect performance.
    – Panther
    Sep 16, 2015 at 15:49
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    To me, the obvious next question is then: why is manual defragmentation still required on Windows after all these years? But that's clearly off-topic for this site. ;-)
    – Oliphaunt
    Sep 16, 2015 at 20:06
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    Two sentences, both wrong. One defrag tool is mentioned right in the question. Another is defragfs. Some related articles: Defragmenting-Linux (linux-magazine.com), How to defrag your Linux system(howtoforge). Also see this question: unix.stackexchange.com/questions/75652/… Sep 16, 2015 at 22:16
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People seem to forget that a good modern defragger is not just defrager, but optimiser as well. Different areas of the hard disk platter read at different speeds. The closer to the centre of the disk, the slower the file read is. A modern defragger will analyse file usage and place frequently read files towards the outer edge of the platter and less frequently used files are moved towards the centre. Some even allow files that are flagged as archives to be pull as close to the centre as possible. I have seen large files on my Linux system broken into 1000's of segments.

I run defrags on my server every month. My temp storage drive where I download my torrents is really bad.

$ xfs_db -r /dev/md6 -c frag

actual 462546, ideal 636, fragmentation factor 99.86%
Note, this number is largely meaningless.
Files on this filesystem average 727.27 extents per file

People that claim linux file systems don't need defragging are just regurgitating what someone else said and have never actually checked.

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  • sadly this is terminal-based, so not a solution unfortunately, but points given because it appears extremely versatile and well worth using ;)
    – Tcll
    Mar 15, 2021 at 3:05
  • also, I think you got a bit confused, the end of the disk is the most dangerous to the heads (so they say) so less frequently used files are stored at the end, while more frequently used files are stored near the center, where there's the least wear ;)
    – Tcll
    Mar 15, 2021 at 3:07
  • For the partition where you torrents are, use btrfs with autodefrag mount option in fstab then forget about the problem! Alternatively run your torrent server/client in a VBOX VM and set your incomplete and complete folders as host-shared folders in the VBOX guest setup. When the torrent finishes, the VM will cut the file from the incomplete shared folder and "flush" it to the complete folder thus re-writing all the blocks contiguously with no fragmentation. This will happen even if it is writing it back to the exact same disk as VBOX forces the re-flush of the file-output-stream. Oct 31, 2021 at 4:54
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Fragview does what I needed and more.

Screenshot of Fragview

As you can see if I click on an area of the map it shows which files are in that area, and how fragmented they are.

I can now use btrfs filesystem defrag should I wish to do so.

Running on Ubuntu 18.04 amd64 with a BTRFS filesystem.

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    with some further research, I found this, which seems to be older than this question: unix.stackexchange.com/questions/30743/…
    – Tcll
    Oct 29, 2021 at 13:59
  • That's btrfs and not OP's EXT4 question. Also for btrfs you should consider autodefrag instead as a mount option in fstab. Oct 31, 2021 at 4:43
  • The filesystem is irrelevant - the app does what is asked. And I'm aware of autodefrag, which definitely doesn't answer the OP's question.
    – Ken Sharp
    Nov 1, 2021 at 14:27
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Currently there are no GUI utilities that offer ease of use

If you use NTFS, ExFAT, or other filesystems without any auto-defrag solution on Linux, you are stuck with cumbersome non-intuitive CLI tools.


The current solution is to use EXT4 or ZFS, which automatically does the brunt work for you to keep your HDDs fast.
Just avoid using more than 90% of your drive

if you use an SSD, fragmentation doesn't matter too much unless a file somehow gets so fragmented, the redirections start degrading performance.

EXT4 can discern an HDD from an SSD and won't kill your write cycles with auto-defragmentation.
just make sure you don't use swap on an SSD ;)

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