Ext4 Users Report Data Loss
The Ubuntu User Forum reports users with data loss after installing applications on the ext4 filesystem. Kernel developer Ted Ts'o is already on top of it.
A user reported as bug #317781 the data loss problem involving a Kubuntu Jaunty installation on the ext4 filesystem: "The first time I had this problem was a few days ago when after a power loss ktimetracker's config file was replaced by a 0 byte version." The problem recurred during a system failure: "After a clean reboot pretty much any file written to by any application (during the previous boot) was 0 bytes." In his case the KDE and Plasma configuration data was reset and MySQL files vanished. Another user ran into the same issue with a Gentoo installation on ext4.
As it became clear that the issue was hitting a number of users, kernel expert and pioneer ext4 developer Theodore Ts'o rushed into the discussion: "The short answer is (a) yes, I'm aware of it, (b) there is a (partial) solution, (c) it's not yet in mainline, and as far as I know, not in an Ubuntu Kernel, but it is queued for integration at the next merge window, after 2.6.29 releases, and (d) this is really more of an application design problem more than anything else."
Ts'o, current chief technologist at the Linux Foundation, took time in his responses to the bug to explain his work on ext4 and hands-on approaches to resolving the data loss problem (especially in this reply). He sees the cause of the problem to be the delayed allocation before a data commit in ext4 of 60 seconds (designed to enhance security and performance). The ext3 interval used to be 5 seconds, which Ts'o says began to be an expectation among developers: "Since ext3 became the dominant filesystem for Linux, application writers and users have started depending on this, and so they become shocked and angry when their system locks up and they lose data --- even though POSIX never really made any such guaranteed."
To help ease the file loss problem, Ts'o recommends for both ext3 and ext4, "If you want to force things to be stored on disk, you must use fsync() or fdatasync()." As an aside, Linux Magazine Online recently aired a video of Ts'o describing the stability of ext4 and its advantages over the experimental btrfs filesystem.
Subscribe to our Linux Newsletters
Find Linux and Open Source Jobs
Subscribe to our ADMIN Newsletters
Support Our Work
Linux Magazine content is made possible with support from readers like you. Please consider contributing when you’ve found an article to be beneficial.
![Learn More](https://www.linux-magazine.com/var/linux_magazin/storage/images/media/linux-magazine-eng-us/images/misc/learn-more/834592-1-eng-US/Learn-More_medium.png)
News
-
Canonical Offers 12-Year LTS for Open Source Docker Images
Canonical is expanding its LTS offering to reach beyond the DEB packages with a new distro-less Docker image.
-
Plasma Desktop 6.1 Released with Several Enhancements
If you're a fan of Plasma Desktop, you should be excited about this new point release.
-
SUSE Offers CentOS 7 Support with Liberty Linux Lite
SUSE's Liberty Linux support offering now includes CentOS 7, which means businesses won't be forced to migrate those servers for some time.
-
Ubuntu's App Center Finally Supports Local Installs Again
If you regularly download .deb files and would prefer a GUI method of installing, Ubuntu has your back.
-
AlmaLinux Now Supports Raspberry Pi 5
If you're looking to create with the Raspberry Pi 5 and want to use AlmaLinux as your OS, you're in luck because it's now possible.
-
Kubuntu Focus Releases New Iterations of Ir14 and Ir16 Laptops
If you're a fan of the Kubuntu Focus laptops or have been waiting for the right time to purchase one, that time might be now.
-
NixOS 24.05 Is Ready for Prime Time
The latest release of NixOS (Uakari) has arrived and offers its usual reproducible, declarative, and reliable goodness.
-
Linux Lite 7.0 Officially Released
Based on Ubuntu 24.04 and kernel 6.8, Linux Lite version 7 now offers more options than ever.
-
KaOS Linux 2024.05 Adds Bcachfs Support and More
With updates all around, KaOS Linux now includes support for the bcachefs file system.
-
TUXEDO Computers Unveils New Iteration of the Stellaris Laptop Line
The Stellaris Slim 15 is the 6th generation and includes either an AMD or Intel CPU