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.
Issue 260/2022
Buy this issue as a PDF
News
-
System76 Teams up with HP to Create the Dev One Laptop
HP and System76 have come together to develop a new laptop, powered by Pop!_OS and aimed toward developers.
-
Titan Linux is a New KDE Linux Based on Debian Stable
Titan Linux is a new Debian-based Linux distribution that features the KDE Plasma desktop with a focus on usability and performance.
-
Danielle Foré Has an Update for elementary OS 7
Now that Ubuntu 22.04 has been released, the team behind elementary OS is preparing for the upcoming 7.0 release.
-
Linux New Media Launches Open Source JobHub
New job website focuses on connecting technical and non-technical professionals with organizations in open source.
-
Ubuntu Cinnamon 22.04 Now Available
Ubuntu Cinnamon 22.04 has been released with all the additions from upstream as well as other features and improvements.
-
Pop!_OS 22.04 Has Officially Been Released
From the makers of some of the finest Linux-powered desktop and laptop computers on the market comes the latest version of their Ubuntu-based distribution, Pop!_OS 22.04.
-
Star Labs Unveils a New Small Format Linux PC
The Byte Mk I is an AMD-powered mini Linux PC with Coreboot support and plenty of power.
-
MX Linux Verison 21.1 “Wildflower” Now Available
The latest release of the systemd-less MX Linux is now ready for public consumption.
-
Microsoft Expands Their Windows Subsystem for Linux Offerings With AlmaLinux
Anyone who works with Windows Subsystem for Linux (WSL) will now find a new addition to the available distributions, one that’s become the front-runner replacement for CentOS.
-
Debian 11.3 Released wIth Numerous Bug and Security Fixes
The latest point release for Debian Bullseye is now available with some very important updates.