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Can anyone explain why is ext4, ext3 or ext2 disk formats that have been used in Ubuntu as default and not others.

Are there any advantages or disadvantages over other? If so, what?

Tim
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A.r. Naresh
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    What other filesystems? If you look closely at them ext -owns- them all. – Rinzwind Aug 06 '14 at 14:07
  • @Rinzwind - is that "is way better than" owns, or they're all based on it? ;-) – Tim Aug 06 '14 at 14:13
  • @tim yes :=) btrfs with mysql is a disaster. For a comparison using Fedora see: http://www.ilsistemista.net/index.php/linux-a-unix/40-ext3-vs-ext4-vs-xfs-vs-btrfs-filesystem-comparison-on-fedora-18.html?start=2 – Rinzwind Aug 06 '14 at 14:22
  • @Rinzwind Not true; it depends on usecase. XFS is unparralleled when it comes to Raid Arrays and large files. I understood ReiserFS to be particularly adept to small files. BTRFS is a feature filesystem (IE Performance is secondary), and so you would use that for entirely different reasons. – Anon Aug 07 '14 at 01:05
  • @Akiva only a few procent of Ubuntu users use raid. And those tend not to be desktop users. Same goes for reiserfs. Cute it is available but on a daily basis not for the Ubuntu desktop user. If you look closely to the features of other filesystems ext comes out on top. – Rinzwind Aug 07 '14 at 04:42
  • @Rinzwind You are misinforming people if you are making statments such as If you look closely to the features(Which Features?) of other filesystems ext comes out on top. Can EXT4 take a sledgehammer to an array of disks like ZFS or BTRFS? Can EXT4 handle large raid arrays like XFS? Is EXT4 as adept for embedded flash like F2FS? I remember on Ubuntu; it used to be a trick to mount /var as a reiserFS filesystem. Yes; EXT4 is stable overall, but in certain usecases which will apply to Ubuntu Users of one stripe or another, it is not the best choice. What do you think? – Anon Aug 07 '14 at 21:34
  • All of your arguments are for the 1% select few that use Ubuntu in extreme situations. "large raid arrays"? ever seen a desktop user with one of those? I have not. Embedded flash on a deskstop? Nope. Never. Ext is THE best choice for the desktop user. If another FS was better we would all be using it on the desktop ;) – Rinzwind Aug 08 '14 at 00:18

2 Answers2

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It is now EXT4.

EXT4 is a sucsessor to EXT3 and 2.

With the first Linux versions, EXT was used:

The extended file system, or ext, was implemented in April 1992 as the first file system created specifically for the Linux kernel.

Inspired by the Unix File System (UFS) it was:

designed by Rémy Card to overcome certain limitations of the MINIX file system.

As both EXT and Linux developed and became more advanced, Linux was designed around EXT, and it became the best filesystem for it to run on, and so EXT developed around Linux.

Each new version of EXT4 became better for linux, with support for things that linux needed.

So why not NTFS?

NTFS doesn't support Linux file permissions so you can't install a Linux system on it.

However,

Linux kernel versions 2.2.0 and later include the ability to read NTFS partitions

Advantages of EXT:

Large file system: Can support volumes with sizes up to 1 EiB and files up to 16 TiB.

Extents: Extents improve large file performance and reduce fragmentation.

Backward compatible with ext3 and ext2

Persistent pre-allocation

Delayed allocation: It delays block allocation until it writes data to disk, improving performance and reducing fragmentation.

Increasing the 32,000 subdirectory limit to be unlimited.

Journal checksumming: Using checksums in the journal to improves reliability, since the journal is one of the most used files of the disk.

Faster file system checking

Improved timestamps: It provides timestamps measured in nanoseconds, needed for critical data on some servers. Also, 2 bits of the timestamp field are added to the significant bits of the seconds field to defer the year 2038 problem for 204 years.

So essentially, it is used because it is better!

Sources:

Wikipedia EXT article

Ask Ubuntu on NTFS

Community
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Tim
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I think the most important reason that ext4 is used as default is that it provides the best mix of stability, speed, and reliability for a the greatest range of workloads. Benchmarks routinely show it near the top in performance in all workloads. Other filesystems may beat it on a single benchmark, but often perform much worse on others. Btrfs has it's strengths but has poor db performance including sqlite (which a lot of desktop applications use). Reiserfs has better small file performance but was unstable.

Really the only other major filesystem that comes close is xfs. Which also has a long development history like ext4. And that has (or had) issues with resizing (shrinking).

People don't want to have to think about their filesystem, and ext4 "just works" in all cases.

clemej
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