ext4 (fourth extended filesystem) is a journalling file system for Linux, developed as the successor to ext3. Use this tag for question that are ext4 specific, generic file system related questions should use tag [filesystem]

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No access to symlink folder on NTFS partition

I am using an NTFS parition for storing data I like to access both from Ubuntu and Windows 7. On my Ubuntu HOME partition, I like to link the folder Assets in order to access it from an application ...
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tune2fs - how much space to reserve on large ext4 filesystem

I am aware that there are several questions concerning how much space to reserve on a filesystem using tune2fs -m, but some of the advice is contradictory, some seems to be relevant only to the ...
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Problems with file system

I created a partition with EXT4 file system and when I'm writing in this partition frequently the Kernel return the following error: Jan 01 01:17:54 infobuffer360 kernel: r7:c0561280 Jan 01 01:17:54 ...
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Have I destroyed data on drive?

I stupidly ran the following command on an external ext4 USB disk, typing /dev/sdb instead of /dev/sda which was the new disk I was setting up: dd if=/dev/zero of=/dev/sda bs=512 count=100 These ...
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Grub rescue after corrupted hard-drive (“read-only filesystem”)

I run xubuntu 12.04 alongside a NTFS storage partition and a windows 8 partition. I moved my MySQL data directory off the xubuntu (ext4) partition, onto the NTFS partition, and did an import of a ...
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What does the 'barrier' mount flag mean in Linux?

The manual for the 'barrier' mount option is: barrier=0 / barrier=1 This disables / enables the use of write barriers in the jbd code.barrier=0 disables, barrier=1 enables (default). ...
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ext4 flags to specify “extents” mode?

I've formatted a new filesystem with and without extents feature just to understand how this feature works. However, when I look at the inode field i_flags I see that this field always has zero value ...
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Do ext(4?) filesystems intrinsically store newer data in a fashion that is more prone to corruption?

I recently had a corrupted ext4 filesystem throwing these errors: kubuntu@kubuntu:~$ sudo mount -t ext4 /dev/sdc2 c1 mount: wrong fs type, bad option, bad superblock on /dev/sdc2, missing codepage ...
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How do distribution installers avoid ext2/3/4 initialization?

When I format a volume with ext4, I have two options regarding initialization. I can either use lazy_itable_init=1 (the default setting) to delay initialization until after the volume is first ...
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110 views

ext4 inodes in use for files that are missing

Executive summary: Every tool I've tried confirms lots of inodes in use on this ext4 partition Every tool I've tried shows me that there are no files on the partition It's not files held open and ...
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What happens to directory entry when a file is renamed

What exactly happens to the directory entry when a file is renamed? Is it that the entry of the oldfile is flushed and the newfile is replaced at it's place or a completely new entry is made at the ...
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195 views

EXT4 Journaling - Problem

Basically my root (/) ext4 partition keeps being mounted as read-only when I apply internal journaling feature. I understand that this should be default, but today I had been trying to apply external ...
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Mapping a physical sector to a filename

I just finished using ddrescue to recover the contents of a failing hard drive. It was able to recover everything but two sectors. How do I figure out which files (if any) occupied those sectors? ...
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ext4 - An entire directory disappeared?

Okay, this has me totally stumped. Background: I'm working on a cryptanalysis homework, trying to break a vigenere cipher with a 26 character key (a shuffled alphabet). Even though there are some 403 ...
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381 views

Understanding ext4/jbd2 transactions

I'm trying to debug a bit of trouble I'm having with I/O latency on a system using ext4, but I'm a bit stumped in that I don't understand its journalling as well as I'd like to. What I'm wondering in ...
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Size Range of ext4 Filesystem Journal

The minimum and maximum sizes respectively for the ext3 filesystem journal are 1,024 blocks and 102,400 blocks. Similarly — what are the minimum and maximum sizes for the journal on an ext4 ...
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443 views

CentOS 5.6 expand ext4 partition , have steps but parted shows as ext3

I have a Adaptec 5805 HW RAID card with a 6.3 TB RAID-6 array (partitioned via Parted GPT, all of which is formatted as ext4 on CentOS 5.6). I want to expand this to 7.5GB and from reading these are ...
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379 views

Mount from auto to manual and changing dir gives errors

I just installed Ubuntu 14.04 and am trying to mount my internal HD to a different location in the /home/username dir (auto-mount mounts it to /mnt/{uuid} ) But I ran into a problem. In Disks, when ...
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593 views

How to find orphan directory entries in a ext4 disk

This comes from a long story of trying to recovering a TrueCrypt volume from a hardware failure (thanks, WD). I ended up with an unencrypted 3TB image that had the files that I want to recover. ...
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310 views

jbd2 journal constant i/o

iotop reports a constant i/o about 3% of [jbd2/vda1-8], I think this is the journal manager for ext4. my fstab is: UUID=X / ext4 defaults,noatime,nodiratime 1 1 tmpfs /dev/shm ...
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248 views

How to limit ext4 filenames to only those filenames legal in FAT?

The ext4 filesystem allows some characters that FAT does not allow, such as :. This has caused me much grief in the past when trying to move files, especially as KDE will delete such files instead of ...
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1k views

Superblock corruption on every boot

I have a Linux Mint 12 install on my laptop. Yesterday I powered it off like I always do and this morning when I started it I was greeted by an error screen. (Translated from Swedish) Fatal ...
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Can skipping `fsck` on boot impact serial-port communication?

I have a bizarre serial-port (RS-232) communications issue (it appears that some data is being dropped, though I'm not sure if it's outgoing, incoming, or both) that I'm observing sporadically. I've ...
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selinux on squashfs with overlayfs

Is it possible to use SELinux on a system with a squashfs root with an overlayfs overlay for read-write operations? On funtoo (gentoo), I booted with SELinux enabled in permissive mode to see what ...
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Reclaiming disk space in Ubuntu

In VMWare the hard disks took 13.6 GB, But with df, only 5.8 GB is occupied I don't quite get it. This Virtual Machine has no snapshots, and I already clicked on refresh button in VMWare Fusion ...
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How to move an ext4 journal

I have an ext4 filesystem on an USB stick and after using it for some time I would like to move the journal to some other blocks, so that the stick lives longer. The journal is described by inode 8, ...
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External USB drive fsck fails on boot

Yesterday I tried setting the fsck flag on fstab to 2 for the external USB HDD I use in my Raspberry Pi, so that it would be checked on boot, like: proc /proc ...
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227 views

ext4 & jbd2 dirty metadata

I have an embedded system based on the RiotBoard, I have the main file system on the MMC set as read-only, and an 8gb usb flash drive for writeable storage. rootfs is debian, linux kernel version ...
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Are the links between the inode and data blocks of a file removed when deleting the file?

Suppose there is only one hard link to a file. When rm the hard link, the inode and data blocks of the file will be marked as unused. But are the links from the inode to the data blocks of the file ...
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73 views

Untar a filesystem to device as normal user but maintaining the correct UID and GID

I'm doing quite a bit of development using Yocto to target an embedded system. As its final output, Yocto generates a tarball of the filesystem, which I then untar onto an ext4 partition of an SD ...
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78 views

Difference between fsarchiver and dump

What is the difference between dump and fsarchiver? Are there features in dump which are not covered by fsarchiver? Can both backup to tape storage for example?
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ETX4-fs error on startup

Hi everybody, today I run dmesg and at the bottom I found some error lines about the device mmcblk0p2. Everything works fine even with those errors but I'd like to understand the problem. I've ...
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Red Hat Enterprise Linux 6.5 remounts root filesystem read-only after hibernating

I have a Lenovo ThinkPad T430 running Red Hat Enterprise Linux 6.5, kernel 2.6.32-431.30.1.el6.x86_64, and my filesystem structure consists of a master LUKS partition holding two logical volumes, one ...
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Find duplicity files after using PhotoRec

I've partly formatted a disc where my duplicity files was stored. I have used PhotoRec to recover the files but now they're all unsorted and without the correct filename. I have the files separated by ...
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164 views

Optimization for an SSD?

I am running Fedora 20 on a Laptop ( Lenovo Ideapad Yoga 2 Pro ) with an SSD. My filesystem is LVM with ext4 as the format option. I am now running Fedora as the only OS on the system with Legacy BIOS ...
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Formatting external USB Harddrive ext4

What is the best way to format a non-ssd harddrive with ext4, for as fast as possible usage with a very low performance computer? I mean, options like disabling things (journaling, ...) that slow ...
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How to blacklist bad blocks from a MD-raid + dm-crypt + ext4?

I have a ext4 partition, on top of a dm-crypt, on top of a MD-RAID 10. One partition (/dev/sdc1) dropped out of the array with a ton of read errors. I ran the manufacturer provided diagnostic tool ...
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Disk partition emptied during tar backup

This morning I was doing a routine backup of my development drive, one of 4 primary partitions on my hard-drive. The script I ran was: filename="/home/Backups/Devi_"`eval date +%Y%m%d`".tgz" touch ...
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How can I delete data from in a hexdump file from one offset to another?

I've created a disk image which was zeroed, formatted to ext4 file system, and then had several various files copied to it. I'm trying to extract these files using a combination of xxd and dd, but ...
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389 views

Howto configure autofs to work with usbsticks formatted with differend filesystems

I have some USB-sticks using fat32 as filesystem and others using ext4. Now I want to configure autofs to mount the sticks automatically. To make sure that the user can write to fat32 sticks I use ...
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Recovering accidentally deleted ext4 partition on DM-0 LVM2 volume spanning across physical drives

I have a setup with some LVM volumes, with following configurations. I accidentally formatted the LV "lvmedia" using the disks program in gnome(I know this was extremely stupid and frustrating) I ...
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Why is EXT4 on LUKS on MD-RAID6 not detected by openSUSE's YaST

For maximum control over the storage configuration I've got two MD-RAID6 devices pre-configured as follows from openSUSE's Rescue system before rebooting the computer into openSUSE's installation ...
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Files Just Go Missing On ext4 Partition (within TrueCrypt Volume)

There are spooky things happening on one of my external hard drives. It's a 3 TB hard drive with: one big partition taking up basically all the storage space there is, and a pretty small partition ...
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GlusterFS on EXT4 is stable enough?

I saw an Article on Rackspace about setting up GlusterFS without using XFS but instead, it uses EXT4. I've been wondering about setup like that since before, to know whether it is production ready ...
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My ext4 partition is corruption-prone possibly because of suspend

I'm using an encrypted ext4 main partition on a Lenovo i7 laptop running Ubuntu 14.04 LTS, currently using the 3.13.0-53-generic x86_64 kernel. After running for multiple weeks without shutting down ...
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ext4: How to save free blocks / inodes to a file

I'd like to save all free blocks / inodes from an ext4 file system to one or more files for further analysis and file recovery. It would be good to create one file for every contiguous set of free ...
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can I boot ext4 usb stick with xubuntu on from a Mac laptop?

is there a way to boot my ext4 formatted "xubuntu" USB memory stick from a Mac laptop? The laptop can identify FAT32 usb memory sticks with ubuntu at boot time, but it cannot identify mine, which is ...
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282 views

Debian..Can't format and mount external HDD

I have been trying to format my 640GB external Hard Drive in command-line and can't seem to get it working. I have done the following in order: sudo fdisk /dev/sda (Deleted any partitions, created ...
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Restoring data from NTFS formatted pre-ext4 partition

MS recovery just formatted my 1TB Backup disk to NTFS which was ext4 before. It was an MBR disk before but now it's a GPT one. Now I'm on SystemResqueCD and can check with the testdisk. What is the ...
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e2fsck -y /dev/sda changed my 6TB disk into 1.8TB

After problems with mount I run e2fsck -y -b BLOCK /dev/sda and it was running for 3 days on 6TB raid 0, when it completed this was the output: /dev/sda: ***** FILE SYSTEM WAS MODIFIED ***** ...