Questions tagged [ext4]

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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Luks and encryption key

I want to check how safe is this solution, I can't find on the web what I have and the differences in scenarios I found make me uneasy especially we are talking about security. What I have is one ...
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mkfs.ext4 not working on 19.1TB logical volume

I can not figure out why its not allowing me to put a filesystem on this logical volume, does anyone have a solution or troubleshoot for this? root@Home-Pi:~# vgs VG #PV #LV #SN Attr ...
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How did my usb change from ext4 to FAT format without me changing it?

I formatted a brand new sandisk usb to ext4 in ubuntu 18.04.2. I have been alternating its use between ubuntu 18.04.3, 64-bit, and debian 10 / armbian, 32-bit. I have been adding files to it until ...
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What is the difference between “dentry” and “inode table” in Linux FS? [duplicate]

Are dentries and inode table same thing? If not what is the purpose of each and where are they stored? How does the filesystem exactly work specifically "ext4" or "xfs"?
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Is there any benefit to using ext4 instead of NTFS? [closed]

Trying to copy an 8GB, encrypted image of one of my flash drives (gotten from "dd" command) onto a flash drive, but flash is FAT formatted. So I'll need to format a new flash to transfer it over to. ...
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Can you set a file's ctime to min(ctime, mtime) [duplicate]

We know that the mtime of a file can be earlier than the ctime when you make copies of files (or, in my case, move files between file systems without successfully retaining timestamps). I see many ...
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36 views

Wrong EXT4 Partition size in luks encrypted partition

I have encrypted my home partition via cryptsetup. Inside the mapper /dev/mapper, i have created a ext4 fs via mkfs.ext4 /dev/mapper/home Now, my home partiotion only has 91 GB. My luks partition ...
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2answers
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ext4 for external hard drive?

If an external hard drive has been formatted from a certain linux-pc with ext4 file system could it be open on other, different linux-pc or it can be open just on the pc on which it was been formatted?...
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CONFIG_EXT4_ENCRYPTION change in .config not persisting after building the kernel

I'm trying to enable encryption config in the kernel for Nvidia Jetson Nano(Tegra), by using menuconfig and rebuilding the kernel. But the specific change is not persisting and is overridden each time ...
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Filesystem got corrupted overnight

OS: xUbuntu 18.04 LTS. I have my OS installed on 256GB SSD: /boot on ext2 / on ext4 (encrypted) That works fine. I have installed the second 1TB HDD recently for storage and backup. Model: WDC ...
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Change filesystem without losing data

I've got 16 nodes of elasticsearch (RHEL 7) - 18TB each, every node has a ext4 filesystem. For better efficency I need to change to XFS filesystem. Is there any tool / way which help me change ...
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Ext filesystem: what happens if a journal is replayed after a crash

I read some things about the ext filesystem journaling, including the man pages, but still do not fully grasp the mechanism. What exactly happens with data and metadata when replaying a journal with ...
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Shutting off power with a non-system r/w ext4 volume mounted

I'm running Raspbian off a read-only ext4 volume. I also have a read/write usb flash volume (ext4, sync) mounted via fstab that runs a simple application that is expected to write occasionally. While ...
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A question on page-management by the virtual file system?

I am trying to get a fairly low level understanding of what happens when a file is opened or changed in linux. Obviously only some of the pages of the entire file, ( i.e. after the blocks on the ...
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directory size inconsistent between “du *” and “du file” [duplicate]

Can someone help me understanding this ? # du -hs * 3,8M depmodwrapper-cross 712M linux-karo 211M u-boot-karo # du --apparent-size -hs * 3,6M depmodwrapper-cross 672M linux-karo 176M ...
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What happens if the limit of 4 billion files was exceeded in an ext4 partition?

What happens if the limit of 4 billion files was exceeded in an ext4 partition, with a transfer of 5 billion files for example?
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2answers
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Is it safe to resize partition in ext4?

I would like to reduce the size of an ext4 partition from my disk and I would like to know if it is possible that my files become corrupted during the operation ? I learn that ext4 file system use ...
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1answer
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Copying ext4 encrypted files

I'm using ext4 encryption. https://wiki.archlinux.org/index.php/Ext4#Using_file-based_encryption Before I decrypt a directory, I can see lots of encrypted filenames in it. I would like to copy the ...
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Renaming a file while it is being written

I'm wondering if this is considered safe. I know the file handles work just fine as long as a link remains, and I know the identifier is the inode rather than the name, but I am not sure how it works ...
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why do some directories have .uuid directory in a directory?

I have seen this quite a few times. In some random directories there is usually a .uuid file or directory therein. The directories are nothing special so as to speak. They are mostly random media ...
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journal_async_commit is not compatible with older kernels. What would you see in this case?

man ext4 mentions a mount option called journal_async_commit. Commit block can be written to disk without waiting for descriptor blocks. If enabled older kernels cannot mount the device. This ...
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47 views

move system partitions to different physical drive with different filesystem

My RHEL7 system is configured like this: Filesystem Size Used Avail Use% Mounted on /dev/mapper/rhel-root 50G 18G 33G 36% / /dev/mapper/rhel-home 504G 147G 357G 30% /home /...
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find extents of each file recursively in a ext4 image file [closed]

I want to log the extents of each file recursively present in a ext4 image file. the physical location of files in ext4 image Any tool i can use for this? or any script? debugfs gives each file ...
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All ext4 files got deleted and the journal can't be found! Is there any way to recover it?

All of the files on my usb stick were deleted by accident (rm -r) but I'm having trouble recovering. When I try to run ext4magic it says "filesystem has no journal" and it mounts as ext2 only. I ...
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If a directory is put in lost+found after running fsck, will it contain all of the original contents?

Let's say I have the following directory structure, in an ext4 filesystem: a/b/{1..9} (in other words, a/b/1, a/b/2, ... a/b/9) Suppose I am writing to a/b, and then I lose power. fsck runs and ...
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Getting sector number from inode or address_space mapping

In am trying to understand how to calculate a sector number from an inode in the ext4 filesystem. Therefore, I am reading ext4_mpage_readpages function. About the function: During a read request, if ...
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Setting noatime via mount options vs no atime updates (A) file attribute

From man chattr When a file with the 'A' attribute set is accessed, its atime record is not modified. This avoids a certain amount of disk I/O for laptop systems. However when I am remounting ...
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49 views

Ext4 - Last write time

I'm currently looking at an issue with data loss and was using the tune2fs utility, and I was wondering what 'Last write time:' refers to. The volume is written to constantly and backups confirm that ...
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Automatically eject HDD on lock screen [duplicate]

I have an external HDD (/dev/sdc) with only one partition (ext4). This particularly hard drive stay connected in my computer all the time, but I don't want to remove it manually. I need a way to ...
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506 views

mount ext4 disk: cannot mount /dev/sdc read-only

I have an SSD disk with an ext4 filesystem on it: $ lsblk -f /dev/sdc NAME FSTYPE LABEL UUID MOUNTPOINT sdc ext4 142b28fd-c886-4182-892d-67fdc34b522a I am ...
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Are released blocks logged in the journal for ext4?

Suppose we have a simple case: ext4 file system with journaling a single file named file, which has no other hard links the inode for file has associated with it only 1 data block My understanding ...
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EXT4 CRC32C checksum algorithms are badly documented

So I'm making some kind of research on EXT4 checksums. I found this page and tried to calculate checksum by myself. I've started with Superblock since it is sounds pretty simple: "The entire ...
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622 views

Should I answer yes to “Clone multiply-claimed blocks<y>?” when running e2fsck?

When running e2fsck -cck /dev/mapper/xxx I am prompted with has 487 multiply-claimed block(s), shared with 84 file(s): ... (inode #221446306, mod time Tue Feb 20 19:48:38 2018) ... (...
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How are ext4fs checksums being calculated?

I've been studying ext4 file system contents and stumbled upon this paragraph: https://ext4.wiki.kernel.org/index.php/Ext4_Disk_Layout#Checksums It says how blocks of data for different structures ...
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Error when move or delete file on ext4 in dpkg info directory

There is a troublemaking empty file (md5sums of kernel 4.19.1) left on my ubuntu system, with has strange owner/group/date/attributes How to fix or workaround this defect file? $ uname -a Linux ...
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Windows removed files copied from Linux and ext4 filesystem

I have an external hard drive with a ntfs filesystem. I have used it to backup the files under my /home (an ext4 filesystem). I choose NTFS only because it is said to be portable between Windows and ...
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2answers
621 views

How can an image file be created for a directory?

How can an image file be created for a directory? For example: https://unix.stackexchange.com/a/90794/674 shows that genisoimage can create an iso image file for a directory. I only know that an ...
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Why is the size of a directory either 0 or 4096? [duplicate]

$ ls -l total 28 drwxrwxrwx 1 t t 4096 May 8 2018 dir1 drwxrwxrwx 1 t t 0 Mar 12 2015 dir2 drwxrwxrwx 1 t t 4096 Jan 17 2014 dir3 drwxrwxrwx 1 t t 4096 Jun 12 2017 dir4 drwxrwxrwx 1 t t ...
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How can I make `fsck` actually check the healthiness of my disk, partitions, filesystems, and LVs?

I want to check the healthiness of my disk, partitions, filesystems, and LVs. So I run fsck. I heard to use fsck on a filesystem, I need to boot into a live Lubuntu from a bootable flash drive and ...
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1answer
45 views

How can I find out the used size of an umounted filesystem?

Is there a way to find out the used size of an umounted filesystem? I want to resize the ext4 / filesystem, so I boot into a live Lubuntu using a Lubuntu bootable flash drive. Since the / filesystem ...
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Warning: The driver descriptor says the physical block size is 2048 bytes, but Linux says it is 512 bytes

My laptop has Lubuntu 18.04 installed, and I boot into a live Lubuntu via a bootable flash drive, and then examine the partitions and filesystems. Is the following warning some serious problem to ...
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41 views

Recommended format for backup extension drive

I have a 2TB seagate extension drive formatted to NTFS. I have been using it for read and write purposes in Windows and read only in Linux. Now that I have decided to get rid of windows, I need to ...
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1answer
550 views

How to use zerofree on a whole disk?

My VirtualBox filesystem looks like: # df Filesystem 1K-blocks Used Available Use% Mounted on /dev/sda2 29799396 5467616 22795012 20% / devtmpfs 1929980 0 1929980 0% /...
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185 views

Can ext4 filesystem withstand a bad sector (unreadable)?

If a hdd bad sector happens in the metadata for /home/user/me on an ext4 fs would that mean data loss for all subdirectories? Background: I know that many users are satisfied with the ext4 ...
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52 views

Shared Hard Drive?

I'd like to set up one external hard drive that would serve as the backup drive for two different laptops, both running Linux. I understand this is problematic b/c each machine will have its own set ...
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1answer
102 views

Does parted have the same functionality as gparted for shrinking an ext4 partition?

I've been Googling about, and it seems the answer is 'no' from anecdotal reports for gparted. However does this apply to parted as well? I'm not talking about risk factors here involved by inputting ...
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364 views

How do inode numbers from ls -i relate to inodes on disk

I'm trying to understand how inode numbers (as displayed by ls -i) work with ext4 partitions. I'm trying to understand whether they are a construct of the linux kernel and mapped to inodes on disk, ...
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421 views

Why can't Windows read Linux filesystems? [closed]

When playing with filesystems and partition, I realized that when I created a ext file system on my USB drive and plug it to Windows, I am forced to format it. On the other end, when building a FAT ...
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72 views

Recover accidentally deleted custom files

I accidentally deleted important custom (not known-or-commercial) files from my scientific researches on image processing. I created the files by collecting raw digital signals from an image sensor. ...
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201 views

processes hanging when trying to access a file

I'm running Ubuntu 16.04.5 and the ext4 filesystem, and I have a file which causes processes to hang when they read it. For example: $ cat /path/to/file.txt and then from a separate terminal: $ ...