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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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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37 views

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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1answer
243 views

Trying to mount ext4 partition from eMMC gives “Invalid Argument” error

I'm trying to set up a custom Linux installation on an Intel Atom (Baytrail) based Android tablet, using Qt 5.5 for device creation. The build system is based on the Yocto project and builds an ...
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1answer
3k views

How to take snapshot of an ext4 filesystem

Is there any way we can take a snapshot of an ext4 filesystem so that we can revert back to it later?
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203 views

How to use tune2fs?

I want to adjust the time interval between ext2, ext3 and ext4 filesystem checks to 180 days? I know that I have to use tune2fs -i 180 but I am not sure about the arguments
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2answers
114 views

Why debugfs doesn't show crtime in nanoseconds?

I am using: debugfs -R 'stat <7473635>' /dev/sda7 to get the file creation time (crtime). Inode: 7473635 Type: regular Mode: 0664 Flags: 0x80000 Generation: 1874934325 Version: ...
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1answer
91 views

Content Explanation Of: /proc/fs/ext4/device_name/mb_groups

I've been wondering, what are the explanation of the columns in the /proc/fs/ext4/device_name/mb_groups file. The columns are: #group: free frags first [ 2^0 2^1 2^2 2^3 2^4 2^5 2^6 2^7 2^8 2^9 2^10 ...
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2answers
140 views

Recovering ext4 superblock

I had an ext4 filesystem in an LV which got destroyed because I accidentally shrunk the partition it was in way too small. After expanding the partition back to the original size I put a new ext4 FS ...
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1answer
193 views

What do “extents” feature do in ext4 filesystem in linux?

I was reading about the ext4 filesystem that it supports compression, encryption and a feature called extents which is used to save disk space. What are extents and how are they are effective for ...
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2answers
403 views

LVM Filesystem recovery

I was trying to resize my LUKS crypt following this https://wiki.archlinux.org/index.php/Resizing_LVM-on-LUKS and I got to the partition resize with parted and seriously screwed things up. I typed 870 ...
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1answer
81 views

EXT filesystem family: Why does the first superblock start at offset 1024?

I was brushing up and diving deeper into filesystem anatomy and in numerous resources it is said to be a requirement that the very first superblock start at an offset of 1024 bytes. I started looking ...
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54 views

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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2answers
9k views

How to fix intermittant “No space left on device” errors during mv when device has plenty of space?

Ubuntu 14.04 on a desktop Source Drive: /dev/sda1: 5TB ext4 single drive volume Target Volume: /dev/mapper/archive-lvarchive: raid6 (mdadm) 18TB volume with lvm partition and ext4 There are ...
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1answer
88 views

EXT4 requiring twice as much storage space - Ubuntu / Beets

I have a question I'm struggling to research an answer for. I have am building a Ubuntu media server at home and decided to carve up my 2TB bulk storage disk into various partitions. I created a ...
2
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1answer
97 views

SSD failiure. grub rescue sees files, but I can't mount drives

I have a 2 year old SSD that apparently has died. 2 out of the 3 partitions are completely unmountable (only EFI boot partition mountable). When i turn on my computer I am greeted with grub rescue ...
3
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1answer
56 views

Cache atime writes

Is there a way to set atime writes to be cached for a very long time? I need atime (that is to say, relatime won't cut it), but I don't want it to effect performance so much. Data loss in of atimes ...
3
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1answer
314 views

ext3 vs ext4 - same disk size, less usable disk space under ext4 comparing to ext3. why?

Files copied from ext3 filesystem do not fit on same size ext4 filesystem. How to reproduce: create two 1GB files, setup loop device for each, create filesystem one ext3, one ext4, mount, rsync ...
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160 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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61 views

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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4answers
365 views

How do I create small disk image with large partitions

I am building a disk image for an embedded system (to be placed on an 4GB SD card). I want the system to have two partitions. A 'Root'(200Mb), and a 'Data' partition(800Mb). I create an empty 1GB ...
5
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1answer
131 views

How to change the extent size in the ext4 file system?

As you can read here , ext4 file system has an extent feature that groups blocks into extents. Each of them can have up to 128MiB contiguous space. In e4defrag , there are lines similar to the ...
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1answer
144 views

Why can't I write to my ext4 partition even with 777 permessions?

When I touch a new file for example I get: touch: cannot touch 'file': permission denied It is a partition that is mounted in the /media directory on demand. I am the owner and I've had it's ...
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3answers
41 views

How to obtain the whole disk activities triggered by file systems under linux?

I want to record the disk access activities called by OS. Such data I want to record are received by disk from OS, including disk sector number, request length, arrival time, read or write. To be ...
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2answers
98 views

Reinstalling Debian: ext4 partition is not primary

I previously had a grub bootloader with crunchbang and win7. Since then I reinstalled win7 which now boots it automatically. I stuck in a Debian install CD that brings me to the stage in the above ...
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2answers
186 views

7-Zip slows down over time on Ubuntu but not Windows

I have a directory called Pages of 2.2 million HTML files (about 80 GB) on an Ubuntu server. I compressed it with 7-Zip using this command: 7z a -mx=9 Pages.7z Pages It took around 5-6 hours to ...
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1answer
199 views

Mark an ext4 filesystem as read-only

I want to create an ext4 filesystem, and add some files to it, then "freeze" it so it is henceforth read-only. I know it's possible to use the ro mount option. But is there some way to indicate in ...
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1answer
181 views

What should I consider when choosing a filesystem for a personal disk archive / cold storage?

I have a few TB of media files that never changes and that I need to store safely. Since it's a personal business it's overkill to set up a disk server et cetera, so I use the simple solution of ...
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4answers
505 views

any large inode size benefits? (ext4)

From some foggy memories I thought I would "improve" the default settings when creating a Linux partition and increased the inode size to 1024, and also turned on -O bigalloc ("This ext4 feature ...
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1answer
1k views

ext4: Can a clean filesystem need journal recovery?

I always thought "clean" is a synonym of does not need journal recovery. However that does not seem to be the case $ sudo file -s /dev/sdc4 /dev/sdc4: Linux rev 1.0 ext4 filesystem data, ...
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117 views

e2fsck repairing an ext4 file system - how to enforce ext4 features?

I have a huge (1.5 TB) corrupted disk with an ext4 fs. The master superblock (and journal) are corrupt, so I am trying to repair it using e2fsck -f -b 7962624 -y /dev/sdb1 Now, the first thing ...
2
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1answer
170 views

do I need fsck.ext4 before mounting a filesystem?

I have a script that mounts /dev/sdc1 to /home. I do not know the state of /dev/sdc1 in advance, it could possibly be "dirty". Do I need to run fsck.ext4 before mounting the filesystem, or has mount ...
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1answer
90 views

Help about CentOS 7 apps & Driver [closed]

I'm using pc for several years but never tried Linux so I'm quite noob in this field. I'm using Autodesk maya, Nuke & will learn houdini very soon. I found that linux works faster for this apps so ...
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2answers
793 views

Why are these files in an ext4 volume fragmented?

I have a 900GB ext4 partition on a (magnetic) hard drive that has no defects and no bad sectors. The partition is completely empty except for an empty lost+found directory. The partition was formatted ...
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2answers
288 views

ext4 file system tuning for storage partition

I searched the Internet, but I was not able to find a satisfying answer to my problem. The Problem I'm encountering currently is, that I'm transitioning my data from a NTFS Partition to a ext4 ...
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31 views

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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265 views

Repeated Ext4-fs error with comm psad: invalid block. Does it mean the SSD is dying?

Configuration : Debian Jessie with SSD. /dev/sda1 is root filesystem, /dev/sda6 is home filesystem. Errors occurs only on /dev/sda1. For the third time, I've got software errors because the root ...
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2answers
65 views

Precaching the list of files of the filesystem

I was wondering where and in what form a list of files and directories is stored on the ext4 filesystem. The problem is that whenever I try to access a certain directory for the first time since boot ...
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1answer
673 views

Lvreduce online on RHEL 6 or centos 6 with ext4 file systems

Is it possible to reduce a mounting lv safely at RHEL6/CentOS6 with ext4 file system? If it is, how can I do that?
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1answer
49 views

testdisk partition recovery

Looking to recover data/partition index from this disk.. ⚡ root@jg  ~  ls /dev/disk/by-label lrwxrwxrwx. 1 root root 10 May 4 21:06 4tb1 -> ../../sde1 drwxr-xr-x. 7 root root 140 May 4 21:06 .. ...
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0answers
193 views

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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0answers
107 views

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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1answer
441 views

Backup Files on ext4 to external NTFS drive

Would there be any problems in copying files on my Linux system with ext4 filesystem to an external drive that is formatted in NTFS? I'm reinstalling my OS and intend to copy these files back to my ...
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4answers
411 views

Prevent file corruption

I have an application that write files into a specific directory at the FS. This system, under no circumstances, can lose a single written file. When I have some problem at the HD, like badblocks or ...
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0answers
77 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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0answers
74 views

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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1answer
1k views

ext4 disk space not reclaimed after deleting files

I recently got a "device full" warning for a 2 Tb external ext4 drive. I deleted a bunch of files, about 90-100 Gb of old system backups, and since I did not want to empty all trash, I deleted the ...
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1answer
315 views

How to use the new Ext4 Inline Data feature ? (storing data directly in the inode)

If I read the Ext4 documentation correctly, starting from Linux 3.8 it should be possible to store data directly in the inode in the vase of a very small file. I was expecting such a file to have a ...
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1answer
99 views

Is it possible to store data directly inside an inode on a Unix / Linux filesystem?

According to this Red Hat bug report (which I am trying to reproduce) it looks like the Netapp filer is able to store data directly in the inode, in case of very small files. Considering I had a FS ...
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1answer
342 views

Can't write on recently created EXT4 partition

On a new external hard drive (Intenso 05-1204-18A), I made (with GParted) two partitions : Disk /dev/sdc: 931.5 GiB, 1000204883968 bytes, 1953525164 sectors Units: sectors of 1 * 512 = 512 bytes ...
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1answer
50 views

writing to ext4, 8GB partition vs 512MB partition

I have a question which is slightly programming related, but it mostly relates to how ext4 works. I have a program which writes 128MB to a file with changing random aligned offsets. I write 256KB ...