ext4 (fourth extended filesystem) is a journaling file system for Linux, developed as the successor to ext3.

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Could I disable ext4's journaling safely in BBWC?

I knew set "nobarrier" flag is safe in BBWC when using ext4,but since "nobarrier" flag couldn't ensure proper order of journal logging and data flushing,then it seems journaling is useless。So is it ...
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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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Could I set flag “barrier=0” when using SSD?

I'm using ext4 filesystem in SSD,when mounting SSD,could I use flag "barrier=0"? I knew this flag is safe for BBU(battery backup unit),but is it safe for SSD?
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Linux: Recover files from .vdi file

Somehow my .vdi (Linux guest OS) file got corrupted. Now I have some files in it (Inside the vdi file) and I want to recover those files. How can I do that?
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How to give Windows partions' file execute permission

I have installed Linux Mint 17 and Windows 8, as dual boot. 500GB hard disk has 5 partitions. Two of them are NTFS and the other 3 are ext4 partitions. When I log into Windows, I can not see any ...
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How can I capture a consistent snapshot of a directory and all its children?

We have an application that periodically backs itself up to a directory on the local file system. Inside this directory are several more files and directories. I want to produce a "snapshot" of all ...
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43 views

What is the difference between fsck options -y and -p?

The ext2/3/4 filesystem checker has two options that seem to be very similar, -p and -y. Both seem to perform an automatic repair, but the manpage states that -p can exit when it encounters certain ...
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60 views

ex4 to btrfs conversion: If I accidentally lose power to the system during the conversion, will I lose the data?

I want to convert the 3TB 80% full ext4 block device into btrfs and I want to estimate the risks involved in the process. If I accidentally lose power to the system during the conversion, will I ...
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ext4 to btrfs conversion: Can I pause, reboot the system and then resume the conversion? [duplicate]

I want to convert a rather big ext4 volume into btrfs. How long will the process will take?
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309 views

Is data=journal safer for Ext4 as opposed to data=ordered?

The default journal mode for Ext4 is data=ordered, which, per the documentation, means that "All data are forced directly out to the main file system prior to its metadata being committed to ...
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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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403 views

“Converting” a filesystem from ext3 to ext4

I've read on some Q&A on this website that one can "convert" an ext3 filesystem to ext4 without formatting, by issuing tune2fs -O extents,uninit_bg,dir_index /dev/dev-name And then running ...
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559 views

External hard drive permissions - ext4

I have an external USB 3 disk drive (2TB capacity) that is most likely going to be moved from machine to machine. The disk has a GUID partition table and an ext4 partition. I am unable to write to the ...
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195 views

Large ext4 partition ridiculously slow when writing

We have four identical Linux servers with a large (5T) hard disk partition. We have Scientific Linux with this kernel: Linux s3.law.di.unimi.it 2.6.32-358.18.1.el6.x86_64 #1 SMP Tue Aug 27 14:23:09 ...
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Optimal rootflags for rootfs for ext4 file system running on USB thumdrive [closed]

I have made myself a bootable USB Debian 7 thumbdrive, using debootstrap. It boots nicely - but occasionally freezes for a bit. I can see the load average is much higher than the running tasks should ...
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1answer
59 views

Where does ext4 store directory sizes?

Where does ext4 store directory sizes? Are they stored in the directory inode? For example, when I run du -h, it returns directories' size instantly, so I don't believe it calculates it at that time. ...
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149 views

How much storage overhead comes along with cryptsetup and ext4?

I want to encrypt the content of a directory in a container with an ext4 filesystem using cryptsetup. The size of the container should be as small as possible and as big as necessary, because I only ...
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What filesystem metadata operations are actually journaled in ext4 & xfs?

I can't find a simple, straight answer about which filesystem metadata operations are actually persisted to the ext4 & xfs filesystem journals. Note that I am not inquiring about what POSIX ...
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124 views

Why does fstrim trim all of the free space on my mdraid mirror after a reboot? [duplicate]

I have a server with 2 SSDs: Model Family: Intel 520 Series SSDs Device Model: INTEL SSDSC2BW240A3F Firmware Version: 400i User Capacity: 240,057,409,536 bytes [240 GB] Sector Size: ...
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I accidentally formatted the wrong volume - is it possible to restore the previous Ext4 filesystem?

I know that a similar question has already been asked. This morning I accidentally formatted the wrong volume, containing mostly video files (about 30GB each). I am currently trying to restore the ...
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123 views

Best parameters for ext4 filesystem to handle virtualbox disk images

I have ext4 partition, which holds disk image files VirtualBox works with. They all are fixed-size images (i.e. files never change their size). They are defragmented as much as possible (with ...
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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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126 views

Reliable way to detect ext2 or ext3 or ext4?

I need to detect a filesystem type from a C/C++ program using the filesystem superblock. However, I don't see much differences between superblocks for ext2 and ext4. The s_rev_level field is the same ...
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ext4 inode size, shown by dumpe2fs

Manpage about mke2fs says "mke2fs creates 256-byte inodes by default". I've formatted my small (320MB) test partition with command: sudo mkfs -t ext4 /dev/sdc1 The defaults for the mke2fs are ...
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237 views

chmod does not change permissions of certain directories

System file: ext4 I changed the owner of files to apache: with the command: chown -R apache: wp.localhost Then, I could not change the permissions of directories in wp.localhost nor the ...
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58 views

Why is it impossible to change the inode count of an ext filesystem?

I know that it isn't possible to change the inode count of an ext filesystem after its creation, but I haven't been able to find any explanation on why it isn't. Can anyone enlighten me?
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ext4, why 70k file takes 88 blocks

[root@xx]# cat -n create_extents.sh 1 #!/bin/bash 2 3 if [ $# -ne 2 ] 4 then 5 echo "$0 [filename] [size in kb]" 6 exit 1 7 fi 8 9 ...
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Are there any tools to recover files from a previously formatted WinNT drive?

I scratched the previous Windows NT filesystem, now I'm running Ubuntu. I've created the whole disk as EXT4. Are there any tools to locate and save some previous Windows files from the original ...
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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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48 views

targeting a specific block with e2fsck to shorten wait

Recently had a LVM'd CentOS 6.5 install get accidentally cold-shutdown. On bootup, it says that the home partition need fscking: /dev/mapper/vg_myserver-lv_home: Block bitmap for group 3072 is not ...
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75 views

Recovering truncated file

I'm in a peculiar situation. While editing a Perl program I accidentally truncated the file to zero length (using an Emacs lisp code I was developing). I need to recover that program... How do I that ...
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recovering /home folder from faulty drive

I was going to try ddrescue to recover data from a faulty (beeping) laptop drive and a primary ext4 partition. Reducing the number of reads from the disk should reduce the recovery time and increase ...
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Fix EXT4-fs bad geometry (block count exceeds size of device)

I have a micro SD card which has a FAT32 partition and an EXT4 partition. The EXT4 partition will no longer mount. dmesg shows the following error: EXT4-fs (sdb2): bad geometry: block count ...
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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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mke2fs difference between -i and -I options

sudo mke2fs Usage: mke2fs [-c|-l filename] [-b block-size] [-C cluster-size] [-i bytes-per-inode] [-I inode-size] [-J journal-options] [-G flex-group-size] [-N number-of-inodes] [-m ...
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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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1k views

Short read while trying to open partition

On my personal home computer running Kubuntu Linux 13.04 I'm having trouble mounting a partition that is very dear to me. My backup policy is to perform a backup about monthly, so I do have a backup ...
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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 ***** ...
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Same file with different content on every read [closed]

I have a problem with a filesystem here on a storage machine. We noticed, that many of the data that comes out of the systems seams to be corrupt, but only with minor problems like CRC errors with ...
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Ext4 - How to enable extra sanity, checksums, validations, tests of any kind?

I'm running Ext4 on a harddrive, and to be perfectly honest, I don't really trust the drive because it's old and has a few badblocks. I have nonessential data on the drive, so if it died tomorrow, ...
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File containing ext filesystem

Let's suppose I create a file, map it to /dev/loop0, and create a LUKS partition inside dd if=/dev/zero of=myfile bs=1M count=1000 losetup /dev/loop0 myfile cryptsetup -c aes-cbc-essiv:sha256 -s 256 ...
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Why is my ext4 filesystem recognizable only on the machine it was formatted on?

Xubuntu liveCD 11.04 running on "bad machine" with mdadm RAID1 array with an unrecognizable ext4 filesystem: To rescue some files, I installed a new hard drive and formatted it to ext4. I copied ...
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100 views

Something like VMware “Changed Block Tracking” (CBT) in linux

I'm wondering if is there any possibility to track changed blocks in linux with an ext3/ext4 filesystem (or a specific one supporting it). I mean a feture like the Changed Block Tracking (CBT) ...
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515 views

How to clean journals in ext3/ext4 filesystem? [closed]

Some preamble: I'm taking bitwise copy of disk devices (via dd command) from twin hosts (i.e. with the same virtualized hardware layout and software packages, but with different history of usage). To ...
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166 views

zerofree verbose returns what?

zerofree -v /dev/sda1 returned 123642/1860888/3327744. The man page does not explain what those numbers are: http://manpages.ubuntu.com/manpages/natty/man8/zerofree.8.html I found some code on ...
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272 views

“unknown partition table” - misconfigured kernel

I was compiling a custom linux kernel for a newly installed machine, and after booting into the new kernel (3.12), the init process fails to find a root device, which I traced to the system getting an ...
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72 views

e2fsck giving some error

I am playing with LVM and while doing lvreduce. I now get this error: [root@localhost raja]# e2fsck -f /dev/vg1/lvol2 e2fsck 1.41.12 (17-May-2010) e2fsck: Superblock invalid, trying backup blocks... ...
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274 views

How can I dump the contents of a filesystem's superblock?

I understand that I can list the location of a filesystem's superblocks using the following commands. Example First get the device handle for the current directory. $ df -h . Filesystem ...
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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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How do I find the offset of an ext4 filesystem?

I have a failing hard drive that is unable to write or read the first sectors of the disk. It just gives I/O errors and that is all there is. There are other areas on the disk that seem (mostly) fine. ...