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I want to use ext4 on my external HDD, but it must be cross-platform. (At least Linux, Win7 & WinXP).

Unfortunately, I haven't found any proper driver allowing Windows to WRITE to ext4. I've found Ext2Fsd, but it only reads ext4.

9. ext4 extent read-only, no size truncating and expanding support

More:

Supported Ext3/4 features:

  • flexible inode size: > 128 bytes, up to block size
  • dir_index: htree directory index
  • filetype: extra file mode in dentry
  • large_file: > 4G files supported
  • sparse_super: super block backup in group descriptor
  • uninit_bg: fast fsck and group checksum
  • extent: reading, writing with no extending.
  • journal: only support replay for internal journal

Unsupported Ext3/4 features:

  • journal: log-based operations, external journal
  • extent: size truncating & expanding, file deletion
  • flex_bg: first metadata group
  • EA (extended attributes), ACL support

Also, I have found a patch for Ext4Fsd v0.50 (here):

New: Matt Wu has made a new release 0.50 at ext2fsd.com. Ext2fsd-0.48-bb8-signed Support for ext4 extents and fix for BSOD on Windows 7.

I don't think it will be safe. Also I've read some words about writing ext4 in Windows could cause data loss on the disk...

What is the External HDD used for? - First, it will store backups, then family movies, pictures. Some music, and etc. It will be connected to a Raspberry Pi, if I finally receive it. It won't really move, just when it is used to migrate computer's data to a new one. The largest files it will store are Clonezilla disk images (I don't know, if they will be large files or not).

Can someone provide a solution for this problem? Or is there NO important enough difference between ext4 and ext3, and I should use ext3? - (If yes, then can I use Ext2Fsd for that ext3 mount?)

Thank you!

Braiam
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antivirtel
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    Have a look at [this](http://www.thegeekstuff.com/2011/05/ext2-ext3-ext4/) page. I don't think that using ext4 for an external hard drive is worth the headache. Why do you not want NTFS or FAT32? Do you need support for _huge_ files? – terdon Aug 23 '12 at 15:20
  • Thank you for the link. I forgot add the situation, and aim of the External HDD. Added to the question now. Otherwise, what size do you mean in `large files`? – antivirtel Aug 23 '12 at 17:01
  • I agree with terdon. Make the drive NTFS and it will be compatible with most OSs out there. – Keltari Aug 23 '12 at 17:26
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    One of the many limitations of FAT32 is that it cannot deal with files larger than 4GB. NTFS (16 EB) and ext4 (16 TB) do not have that limitation. – terdon Aug 24 '12 at 03:54
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    Neither the linked duplicate nor the accepted answer actually answer this question. – Reticulated Spline Jul 03 '20 at 16:08
  • I would like to submit a worthwhile use case of my own: I have a large amount of Linux Workstation drives, these are all in offline locations. The changeover happened and I am now stuck with usb disks and some hard drives, and a machine with Win10 on it. I have a lot of personal files on these drives and the free space I have is on those drives along with some of the projects I am working on. Actually that is irrelevant, the relevant part is how is it 2022 and ext4 is still not recognized by windows (yes im aware, its an old question but this is a new comment) – osirisgothra Jun 25 '22 at 16:04

3 Answers3

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Paragon software offers ExtFS for Windows 2.0 for free for personal use. It allows to read and write ext2 ext3 and ext4 from all Windows OS

http://www.paragon-software.com/home/extfs-windows/

It appears to be somewhat similar to Linux Reader from Diskinternals, that can mount all ext, HFS and ReiserFS too, but read-only.

http://www.diskinternals.com/linux-reader/

Albert
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    Is Paragon adware/malware free and completely safe? Have you used it yourself? – Rajib Nov 18 '13 at 15:01
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    The Paragon software is not working for me (ext4 created from Ubuntu 14.04 LTS), on Windows 8 got only read access. When creating a file it crashes with a message informing me that the new file is too big - empty txt file. – monnef Mar 26 '15 at 08:50
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    I went through the pain to download, install and register it. Theyr require an email to send serial to and I used a "10 minute email". Probably spam supported. – Gunslinger Sep 03 '15 at 17:38
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    But it did manage to mount an ext4 partition to my windowns 10 read/write. – Gunslinger Sep 03 '15 at 17:44
  • Unfortunately on win 7 when writing over files on ext4 partition it corrupts them. – Archibald Mar 02 '17 at 16:25
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    Paragon isn't working for me: https://superuser.com/questions/1189512/paragon-extfs-cant-write-files-to-ext4-drive-from-windows-10 – Aaron Franke Mar 17 '17 at 01:28
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    Paragon is no longer working, there is no download link, there is no buy link, they actually ask you to "call their sales team" so that's a big nope. Looks like the only option is going to be linux-reader or windows WSL2 – Shodan Dec 22 '21 at 07:28
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I would use NTFS instead. It can easily be read/written to by Linux, Windows and OS X (among others).

Considering the intended use and the fact that it is an external drive, I see no reason why you should go through the hassle that using ext4 will be.

If this were your primary hard drive, perhaps the advantages of ext4 (briefly, less drive fragmentation and slightly improved performance, for more information see here) would be worthwhile. I doubt you will even notice a difference on an external USB drive. The bottleneck will be the rate of data transfer over the USB cable.

For most users, the only obvious benefit of ext4 over NTFS is that ext4 allows file names with special characters (? & % etc). Such file names, however, are both a bad idea and of no particular interest to you.

EDIT: In answer to B. Roland's question about defragmenting, yes, there are two ways I know of to defragment an NTFS drive under linux. One is an open source tool called shake. I haven't used it but it seems to work. The other is simply copying all data from the external drive, deleting everything from the drive and then copying everything back. Finally, since your drive will also be accessed under windows you can use the windows defragmenter.

I think, however, that you are attaching way too much importance to drive defragmentation. Have a look here for a simple explanation of fragmentation. Briefly, a fragmented drive is one where the files on the drive are not stored in contiguous blocks but spread out across the drive. This is usually caused by changing a file's size after it has been written. So, say you save a 1 MB file on your drive. You then modify the file and its size goes up to 20 MB. If there is not enough free space at the position where the file was created, this extra data will be written to a different part of the hard drive. In other words, the file will be fragmented.

This kind of thing is not likely to occur very often in a drive used for storing "backups, then family movies, pictures. Some music, and etc". Most of these files will never change in size, and therefore, will never fragment the drive.

In addition, even if your drive is fragmented, you don't really care. Fragmentation can be a problem for system drives where you can have many I/O operations per second. In those cases you can notice a decrease in drive performance. As I said before, on an external drive I don't think you will be able to detect this, even if it does happen.

So, in conclusion, you almost certainly will not need to defragment an NTFS formatted external HDD. However, if you really want to, you can do it both in Linux and in Windows.

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terdon
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    I completely agree. NTFS (and FAT32) are simply the most portable file systems out there. – Keltari Aug 24 '12 at 05:45
  • Will the NTFS worth data fragmentation problem? Ext4 has no fragmentation. Otherwise it has USB 3.0 connector, so it is much faster than a normal USB 2.0. Portability is secondary. It is a WesternDigital My Book Essential (1TB) – antivirtel Aug 24 '12 at 07:57
  • @B.Roland IMHO, yes. Granted NTFS will have more fragmentation but, again, this should not be a serious problem on an external, non system drive. I really think using ext4 is simply not worth the effort. I very much doubt that you will see _any_ improvement at all. It may be there, but it will probably not even be detectable unless you run benchmarks. I really doubt you will notice any difference as a user. – terdon Aug 25 '12 at 14:08
  • Oh, ok @terdon, if you add something about how to defragment NTFS on a Linux, I'll accept your answer. (eg. http://www.linuxquestions.org/questions/linux-newbie-8/how-to-defragment-in-linux-ubuntu-710920/) – antivirtel Aug 26 '12 at 08:38
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    I disagree that it can be *easily* read/written by all. There's an overhead to ntfs-3g on *nix. – eichoa3I May 26 '13 at 21:05
  • @jhstuckey I never claimed there was no overhead. Still NTFS is the best filesystem that can be easily read/written by the greatest number of OSs. By _easily_ I mean easily for the user not necessarily the kernel. – terdon May 27 '13 at 13:06
  • In fact NTFS **does** support POSIX filenames but default it will be disabled on windows because of compatibility reasons – phuclv Aug 24 '13 at 02:51
  • http://en.wikipedia.org/wiki/NTFS "In Posix namespace, any UTF-16 code unit (case sensitive) except U+0000 (NUL) and / (slash)." http://support.microsoft.com/kb/100625 – phuclv Jun 08 '14 at 01:50
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    I did not expect that the (accepted) answer to the question "How to mount read-write an ext4 partition on Windows?" would be to use NTFS instead when clicking on this link from Google. I am in a situation where it is no option to use NTFS, it is ext4. I want to know how to read/write ext4 from windows (thats how I got to this URI). I am not searching for good advice. Though I can imagine this may be the answer to the OPs question. – Mike de Klerk Aug 20 '15 at 05:31
  • @MikedeKlerk in the case of the person asking the question, using NTFS was the better solution. Have a look at the other answers for different solutions. – terdon Sep 03 '15 at 12:17
  • NTFS supports POSIX namespace so it can store special characters like `*?:`... in file names without problem. It's just the limitation of win32 namespace – phuclv Jun 04 '17 at 03:51
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    First, that was not the question. Second, NTFS implements permissions differently than Linux. It runs inefficiently on Linux according to tests by android developers, and it does not support many features such as extended attributes and filetype storage. – Robert Wm Ruedisueli May 21 '19 at 23:52
  • @RobertWmRuedisueli perhaps, but as you can see it was the answer. The OP just wanted to have an *external* drive that could be used in both Linux and Windows. The best approach for that is ntfs and not ext. Neither efficiency nor extended features are relevant in this particular case. – terdon May 22 '19 at 06:36
  • @terdon I agree on that front. I wish that there was better support for EXT4, F2FS and BTFS in Windows. This is especially important to Android developers and modders, as Android devices and VMs commonly use these filesystems for their Data partitions. – Robert Wm Ruedisueli Jul 03 '19 at 18:33
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    On Raspberry Pi, NTFS performance is very low. For the same disk, NTFS's write speed was about 30MB/s, whereas EXT4's write speed was about 100MB/s. – Damn Vegetables Jul 18 '20 at 20:56
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    "Just use NTFS" is a really bad answer to "How to mount read-write an ext4 partition on Windows?" – Shodan Dec 22 '21 at 07:29
  • @shodan OK. Please downvote instead of commenting then. – terdon Dec 22 '21 at 08:21
  • NTFS is indeed better supported on Linux than ext4 is on Windows. But that says something about the commitment of the Linux community, not about the quality of the filesystem. This answer is definitely not a good answer to this question. The question may state it is needed to transfer files between OS's, but it explicitly asks to use ext4. – FHannes Jan 11 '22 at 09:02
  • @FHannes please downvote instead of commenting. That's what the votes are for. This is not a discussion forum, and I am frankly quite tired of receiving comments _a full decade_ after posting an answer that actually solved the problem the OP was having (as you can see, the answer was accepted). You are, of course, free to disagree, but please do so by voting instead of adding yet more noise. At the very least, take the time to read the existing comments and see if you actually have anything to add or if you are repeating what others have said in the past ten years. – terdon Jan 11 '22 at 09:44
  • I disagree, in my 30+ years of Linux/Windows experience, I have found NTFS to be shoddy and very unreliable compared to Ext filesystems. Ever tried recovering one when you lost the records? Doubtful. And it has to be optimized in order to keep it from being a shattered, tattered mess. I even switched my field of study to Linux because of how terrible the support for other filesystesm are. Only reason people say NTFS is well supported, is because LINUX SUPPORTS IT. If it wasn't for that fact, nobody would even be saying it, but its performance in Linux is just as terrible as it is in Windows. – osirisgothra Jun 25 '22 at 16:09
  • @osirisgothra I don't understand why you chose to rant at me 10 years after an answer was posted, but if you read it again, you might find that I never said NTFS was good, I only said that it is supported by both Linux and Windows, so it makes more sense to use it on an _external_ drive designed to be used by both systems than to try to wrangle Windows to support ext. Next time, instead of leaving such an aggressive and, frankly, pretentious comment, just downvote and post a better answer. – terdon Jun 25 '22 at 16:34
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If you want to SOME of the features of EXT4, you can use them using tune2fs to add the features to an EXT3 partition. The latest Ext2FSD release notes should list which features you can enable. You may want to read the tune2fs man page, there are some hints on how to handle writing to the filesystem in the header that can be beneficial to set for a backup drive that requires reliability, or to set to the other extreme for a drive containing non-critical files that require fast access and fast read-write times

You don't really need extended attributes and ACLs, and depending on your Linux setup they may not even be active to begin with. Incompatibilities between Windows and Linux on permissions makes it ill-advised to use this feature cross platform, even if supported.

Robert Wm Ruedisueli
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