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
-
NVIDIA Released Driver for Upcoming NVIDIA 560 GPU for Linux
Not only has NVIDIA released the driver for its upcoming CPU series, it's the first release that defaults to using open-source GPU kernel modules.
-
OpenMandriva Lx 24.07 Released
If you’re into rolling release Linux distributions, OpenMandriva ROME has a new snapshot with a new kernel.
-
Kernel 6.10 Available for General Usage
Linus Torvalds has released the 6.10 kernel and it includes significant performance increases for Intel Core hybrid systems and more.
-
TUXEDO Computers Releases InfinityBook Pro 14 Gen9 Laptop
Sporting either AMD or Intel CPUs, the TUXEDO InfinityBook Pro 14 is an extremely compact, lightweight, sturdy powerhouse.
-
Google Extends Support for Linux Kernels Used for Android
Because the LTS Linux kernel releases are so important to Android, Google has decided to extend the support period beyond that offered by the kernel development team.
-
Linux Mint 22 Stable Delayed
If you're anxious about getting your hands on the stable release of Linux Mint 22, it looks as if you're going to have to wait a bit longer.
-
Nitrux 3.5.1 Available for Install
The latest version of the immutable, systemd-free distribution includes an updated kernel and NVIDIA driver.
-
Debian 12.6 Released with Plenty of Bug Fixes and Updates
The sixth update to Debian "Bookworm" is all about security mitigations and making adjustments for some "serious problems."
-
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.