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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]

118
votes
10answers
157k views

How do I know if a partition is ext2, ext3, or ext4?

I just formatted stuff. One disk I format as ext2. The other I want to format as ext4. I want to test how they perform. Now, how do I know the kind of file system in a partition?
76
votes
5answers
36k views

Birth is empty on ext4

I was just reading up on the Birth section of stat and it appears ext4 should support it, but even a file I just created leaves it empty. ~ % touch test ...
71
votes
7answers
220k views

Tell fs to free space from deleted files NOW

Is there a way to tell the kernel to give back the free disk space now? Like a write to something in /proc/ ? Using Ubuntu 11.10 with ext4. This is probably an old and very repeated theme. After ...
43
votes
4answers
174k views

Recovering ext4 superblocks

Recently, my external hard drive enclosure failed (the hard drive itself powers up in another enclosure). However, as a result, it appears its EXT4 file system is corrupt. The drive has a single ...
41
votes
4answers
107k views

Can overwritten files be recovered?

I am not talking about recovering deleted files, but overwritten files. Namely by the following methods: # move mv new_file old_file # copy cp new_file old_file # edit vi existing_file > D > ...
33
votes
3answers
2k views

Why doesn't my exactly 100 MiB partition at 1 KiB block size have the corresponding available blocks/space?

I have a very high density virtualized environment with containers, so I'm trying to make each container really small. "Really small" means 87 MB on base Ubuntu 14.04 (Trusty Tahr) without ...
32
votes
2answers
29k 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 the ...
28
votes
1answer
4k views

Why is ext4 only recommended up to 16 TB?

In the ext4 wiki article I've seen that ext4 can be used up to 1 EiB, but is only recommended up to 16 TiB. Why is that the case? Why is XFS recommended for larger file systems? (ELICS: Explain me ...
25
votes
3answers
2k views

How to delete a file named “filen/ame” (with slash) on an ext4 filesystem in debugfs?

Playing with e2fsprogs debugfs, by change/accident, a file named filen/ame was created. Obviously the forward slash character / serves as the special separator character in pathnames. Still using ...
22
votes
2answers
2k views

What happens when I kill 'cp'? Is it safe and does it have any consequences?

What are the consequences for a ext4 filesystem when I terminate a copying cp command by typing Ctrl + C while it is running? Does the filesystem get corrupted? Is the partition's space occupied by ...
22
votes
5answers
40k views

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 ...
21
votes
3answers
54k 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 ...
21
votes
2answers
80k views

Why ext4 File System is better than NTFS? [closed]

For a presentation, I need to show ext4 File System is better than NTFS. I searched and got nice article on both ext4 and NTFS http://en.wikipedia.org/wiki/Ext4 http://en.wikipedia.org/wiki/NTFS But ...
19
votes
1answer
38k views

How do I determine the new size for resize2fs?

I want to shrink an ext4 filesystem to make room for a new partition and came across the resize2fs program. The command looks like this: resize2fs -p /dev/mapper/ExistingExt4 $size How should I ...
19
votes
5answers
57k views

Cannot remove file: “Structure needs cleaning”

I have an external hard drive which is encrypted via LUKS. It contains an ext4 fs. I just got an error from rsync for a file which is located on this drive: rsync: readlink_stat("/home/some/dir/...
19
votes
2answers
2k 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 ...
18
votes
2answers
2k views

What ext4 functionality does btrfs not support?

btrfs (often pronounced "better fs") has quite a few features that ext4 lacks. However, comparing the functionality of btrfs vs ext4, what is lacking in btrfs?1 In other words, what can I do with ...
17
votes
2answers
11k views

Can the same ext4 disk be mounted from two hosts, one readonly?

I know that mounting the same disk with an ext4 filesystem from two different servers (it's an iSCSI vloume) will likely corrupt data on the disk. My question is will it make any difference if one of ...
17
votes
1answer
24k 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?
17
votes
2answers
11k views

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). This ...
16
votes
4answers
19k views

Can I port user permissions across computers for an ext4 external hard drive?

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 ...
16
votes
2answers
20k views

largefile feature at creating file-system

Is useful to use -T largefile flag at creating a file-system for a partition with big files like video, and audio in flac format? I tested the same partition with that flag and without it, and using ...
16
votes
2answers
37k views

What's the meaning of output of lsattr

I'm wondering what the output of lsattr means.It prints so oddly as follows,when I have tried: lsattr /usr. $ lsattr /usr -----------------e- /usr/local -----------------e- /usr/src -----------------...
16
votes
1answer
8k views

What does fsck -p (preen) do on ext4?

I was reading a blog post about filesystem repair and the author posted a good question… fsck -p is supposed to fix minor errors automatically without human intervention. But what exactly will it fix ...
16
votes
1answer
22k views

How can I mount filesystems with > 4KB block sizes?

I have a 3TB hard disk pulled out of a WD Mybook Live NAS. The partition table is as follows: Model: ATA WDC WD30EZRS-11J (scsi) Disk /dev/sdb: 3001GB Sector size (logical/physical): 512B/4096B ...
16
votes
1answer
2k views

Is there a way to measure the progress of ext4lazyinit?

I had asked a question about ext4lazyinit here. From all I have read and understood, it simply allows you to start using the hdd without creating all the inodes for your file system. The only way ...
14
votes
5answers
4k views

Millions of (small) text files in a folder

We would like to store millions of text files in a Linux filesystem, with the purpose of being able to zip up and serve an arbitrary collection as a service. We've tried other solutions, like a key/...
14
votes
3answers
11k views

ext4: How to account for the filesystem space?

I've recently formatted a 1.5 TB drive with the intention of replacing ntfs with ext4. Then I noticed that the files I saved don't fit on the new partition. df: ext4 (ext3 & ext2 show the same ...
14
votes
2answers
14k views

Why is (free_space + used_space) != total_size in df? [duplicate]

Possible Duplicate: ext4: How to account for the filesystem space? I have a ~2TB ext4 USB external disk which is about half full: $ df Filesystem 1K-blocks Used Available Use% ...
14
votes
2answers
6k views

How can I mount a filesystem, mapping userids?

I can successfully mount an ext4 partition, the problem is that all the files on the partition are owned by the user with userid 1000. On one machine, my userid is 1000, but on another it's 1010. My ...
14
votes
1answer
7k views

Why is this empty directory 3.5MB?

I've just read this question: What does size of a directory mean in output of 'ls -l' command? ...which doesn't quite answer my question. Basically, I'm moving files onto a NAS. The folders I'...
14
votes
1answer
14k views

Advantages/disadvantages of increasing “commit” in fstab

I have done many obscure system optimizations in the past, but I got rid of most of them after powertop told me I should set my USB ports to autosuspend, which forced them to an eternal sleep, and ...
13
votes
1answer
3k views

Is disabling barriers for ext4 safe on a laptop with battery?

The manual page says about the barrier option for ext4: Write barriers enforce proper on-disk ordering of journal commits, making volatile disk write caches safe to use, at some performance penalty....
13
votes
4answers
1k views

independently verify that TRIM indeed works on SSD

I have a LUKS partition /dev/sda1 which I luksOpen with --allow-discards: cryptsetup --allow-discards luksOpen /dev/sda1 root I then mount the ext4 filesystem with discard option: grep /dev/mapper/...
12
votes
2answers
12k views

Is it possible to change Inode count on an ext4 filesystem? [duplicate]

Possible Duplicate: How can I increase the number of inodes in an ext4 filesystem? I have a homemade NAS with Debian Wheezy 64bit. It has three disks - 2x2TB and 1.5TB, pooled together using ...
12
votes
2answers
24k views

How can I shrink a LUKS partition, what does `cryptsetup resize` do?

I am in progress of resizing a LUKS encrypted partition that contains a single ext4 filesystem (no LVM or something). The cryptsetup FAQ recommends to remove the old partition and recreate it, but ...
12
votes
4answers
13k views

Should a laptop user switch from ext4 to btrfs?

Related to this. I'd like to take advantage of an OS switch to upgrade to BTRFS. BTRFS claims to offer a lot (data-loss resiliency, self-healing if RAID, checksumming of metadata and data, ...
12
votes
2answers
12k views

Which filesystem to backup is the best? [closed]

I just bought a disk to backup all my documents and to store it apart and I don't know what is the filesystem under Linux that gave me better reliability. Maybe I'll backup one time each month and it ...
12
votes
1answer
624 views

What could explain this strange sparse file handling of/in tmpfs?

On my ext4 filesystem partition I can run the following code: fs="/mnt/ext4" #create sparse 100M file on ${fs} dd if=/dev/zero \ of=${fs}/sparse100M conv=sparse seek=$((100*2*1024-1)) count=1 2&...
11
votes
1answer
355 views

Does inode number determine what files were created earlier than others?

In an ext4 filesystem, suppose that file1 has inode number 1, and that file2 has inode number 2. Now, regardless of any crtime timestamp that might be available, is it wrong to assume that file1 was ...
11
votes
1answer
3k views

Different UID/GID when using an ext4 formatted USB drive with another computer

The problem of using a filesystem like ext4 on a USB stick or memory card is that when it's mounted into another system the disk's UID/GID might not be present. Can this be fixed with a mount option?
11
votes
1answer
10k views

Find which files are affected by bad blocks on ext4 filesystem

I have an ext4 filesystem that recently developed some bad sectors. Running fsck.ext4 -c finds and remembers the bad blocks. How can I find which files (if any) included these bad blocks so I can ...
11
votes
2answers
5k views

Why is deleting files by name painfully slow and also exceptionally fast?

Faux pas: The "fast" method I mention below, is not 60 times faster than the slow one. It is 30 times faster. I'll blame the mistake on the hour (3AM is not my best time of day for clear thinking :).. ...
10
votes
2answers
20k views

How to make ext4 filesystem sparse?

I am using Linux as guest OS in VirtualBox. I deleted huge number of files from its filesystem. Now i want to shrink the filesystem image file (vdi). The shrinking works by compressing filesystem ...
10
votes
3answers
6k views

ext2/3/4 reserved blocks percentage purpose [duplicate]

I know that this feature dates back 20 years but I still would like to find out What is the purpose of the reserved blocks in ext2/3/4 filesystems?
10
votes
4answers
6k views

Does any file system implement Copy on Write Mechanism for CP

We have seen OS doing Copy on Write optimisation when forking a process. Reason being that most of the times fork is proceeded by exec , so we don't want to incur the cost of page allocations and ...
10
votes
4answers
54k views

How can I fsck a partition when the device reads as busy (but has been confirmed otherwise)?

I'm attempting to run fsck -p /dev/sda5 to repair errors on an ext4 partition, however the command outputs fsck from util-linux-ng 2.17.2 fsck.ext4: Device or resource busy while trying to open /dev/...
9
votes
6answers
15k views

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. ...
9
votes
1answer
3k views

Why could the size of the “dot” file “.” exceed 4096?

Today I found an "empty" directory with a size of 4MB. It had no visible contents, so I tried ls -lah. This showed me some hidden files (not very large). Searching for the reason why the directory ...
9
votes
4answers
1k views

Are short-lived files flushed to disk?

My program creates many small short-lived files. They are typically deleted within a second after creation. The files are in an ext4 file system backed by a real hard disk. I know that Linux ...