A similar looking question asks for the reason why the upper file limit could be 2 TB in ext2. I am trying to understand but the Documentation on ext2 but find this hard. Please correct me if I'm wrong: - Blocks can be 1 - 4 KB in size - available amount of blocks is based upon a 32-Bit value: 232 = 4.294.967.296 blocks In the documentation I found: 231-1 = 2.147.483.647 addressable Blocks. I miss 2.147.483.649 Blocks. My **guess** is that this is »reserved« for the *Superblock*, the *Block Group Descriptors* , their backups etc. (correct?) Question ---------- **How exactly are the file size limits calculated in ext2** And, just in advance: Is – and if so – how far can this be translated to ext3 and ext4 (or other file systems... please?) – I'm still far from them and not lazy to look this up myself; just confused about where the basics come from .

details ------- As detailed [here](https://unix.stackexchange.com/a/259712/38638) , the /boot on this Debian Jessie had filesystem type=ext2 $ mount | grep -e '^/dev/' /dev/sda3 on /boot type ext2 ... ... and was unable to upgrade its GRUB2 $ sudo apt-get dist-upgrade ... Setting up grub-common (2.02~beta2-22+deb8u1) ... Setting up grub2-common (2.02~beta2-22+deb8u1) ... Setting up grub-pc-bin (2.02~beta2-22+deb8u1) ... Setting up grub-pc (2.02~beta2-22+deb8u1) ... Installing for i386-pc platform. Installation finished. No error reported. Installing for i386-pc platform. grub-install: warning: File system `ext2' doesn't support embedding. grub-install: warning: Embedding is not possible. GRUB can only be installed in this setup by using blocklists. However, blocklists are UNRELIABLE and their use is discouraged.. At about this point, my console went to a [curses TUI](https://en.wikipedia.org/wiki/Curses_%28programming_library%29) to present a dialog with title=Configuring grub-pc and body telling me that GRUB failed to install: Do you want to continue anyway? If you do, your computer may not start up properly. Writing GRUB to boot device failed - continue? I hit button=No. At that point, * the GRUB2 packages={grub-common, grub-pc, grub-pc-bin, grub2-common} were installed (per apt-get and aptitude) but not fully configured (per message above). * I had the following questions --------- **1.** Should I now should update my {/dev/sda3, /boot} from filesystem type=ext2 to something else (presumably ext4)? If I am misunderstanding the situation: what do I need to know? Is there something I should do to debug? If I am *not* misunderstanding: what's the {easiest, most reliable, least disruptive} way to convert /boot's filesystem, on Debian (which this box is running)? [fstransform](https://packages.debian.org/search?keywords=fstransform) ? **2.** Should I should now reconfigure GRUB2? E.g., how do I (or another Debian user in same situation) recreate the Setting up actions (see second text block) induced by the package install? answers ------- **1.** It seemed clear to me that I should update my {/dev/sda3, /boot} from filesystem type=ext2 to ext4, which I did with [fstransform](https://github.com/cosmos72/fstransform) (installing its [Jessie package](https://packages.debian.org/search?keywords=fstransform) as detailed [here](https://bitbucket.org/snippets/tlroche/eyXRq) . This seemed to go well (except for [one problem](https://github.com/cosmos72/fstransform/issues/5)) . However this filesystem upgrade may not have been necessary, per Jordan Uggla [here](http://lists.gnu.org/archive/html/help-grub/2016-02/msg00019.html) . **2.** Per [Uggla's post](http://lists.gnu.org/archive/html/help-grub/2016-02/msg00019.html) , I reconfigured GRUB2 with sudo dpkg-reconfigure grub-pc --frontend=text as detailed [here](https://bitbucket.org/snippets/tlroche/E8rAx) . I now see and boot to the updated kernel and have no boot-time error messages.

debian11. I copied EXT2 filesystem from some dump file. I'm not sure if this file is intact or has no errors. $ file ext2file ext2file: Linux rev -1358692254.9334 ext2 filesystem data (mounted or unclean), UUID=a200288c-6200-14af-a200-2c8c620018af, volume name "\242" (64bit) (large files) I tried extfstools, but it can't (possibly I used it incorrectly) $ ./ext2rd ext2file ./:savedir Segmentation fault Is it possible to extract files from it?

I used binwalk to scan firmware image, uncompressed & raw RAM dump. When scan for signatures with -I flag there is reference to Linux EXT filesystem: DECIMAL HEXADECIMAL DESCRIPTION -------------------------------------------------------------------------------- ... ... 2148245 0x20C795 Linux EXT filesystem, blocks count: 1048741, image size: 1073910784, invalid state invalid error behavior invalid major revision rev 611745794.9334, ext2 filesystem data (mounted or unclean), UUID=a200288c-6200-14af-a200-2c8c62006200, volume name "¢" I want extract that filesystem use dd command: dd if=image.out of=ext2-filesystem bs=1 skip=2148245 count=1048741 On output I got file 1,0 MiB (1 048 741 bytes). I'm not sure that this is correct result, the file is too small. What should be the correct command for this? EDIT: GNU Coreutils, $ dd --version dd (coreutils) 8.32

How approximately calc bytes-per-inode for ext2? I have 7.3GB storage (15320519 sectors 512B each). I have made ext2 filesystem with block size 4096 mke2fs /dev/sda2 -i 524288 -m 0 -L "SSD" -F -b 4096 -U 11111111-2222-3333-4444-555555555555 -O none,filetype,sparse_super,large_file Filesystem label=SSD OS type: Linux Block size=4096 (log=2) Fragment size=4096 (log=2) 15104 inodes, 1915064 blocks 0 blocks (0%) reserved for the super user First data block=0 Maximum filesystem blocks=4194304 59 block groups 32768 blocks per group, 32768 fragments per group 256 inodes per group Superblock backups stored on blocks: 32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632 Usually all my files has size 100kB (and about 5 files can be 400MB). I try to read this and this . But still not clear how approximately calc bytes-per-inode? Current 524288 is not enough, for now I can't make new files in sda2 but still have a lot of free space. P.S. Extra info # df -T Filesystem Type 1K-blocks Used Available Use% Mounted on /dev/root ext4 146929 84492 59365 59% / devtmpfs devtmpfs 249936 0 249936 0% /dev tmpfs tmpfs 250248 0 250248 0% /dev/shm tmpfs tmpfs 250248 56 250192 0% /tmp tmpfs tmpfs 250248 116 250132 0% /run /dev/sda2 ext2 7655936 653068 7002868 9% /mnt/sda2 # df -h Filesystem Size Used Available Use% Mounted on /dev/root 143.5M 82.5M 58.0M 59% / devtmpfs 244.1M 0 244.1M 0% /dev tmpfs 244.4M 0 244.4M 0% /dev/shm tmpfs 244.4M 56.0K 244.3M 0% /tmp tmpfs 244.4M 116.0K 244.3M 0% /run /dev/sda2 7.3G 637.8M 6.7G 9% /mnt/sda2 # fdisk -l Disk /dev/sda: 7.45 GiB, 8001552384 bytes, 15628032 sectors Disk model: 8GB ATA Flash Di Units: sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disklabel type: dos Disk identifier: 0x0a19a8af Device Boot Start End Sectors Size Id Type /dev/sda1 309 307508 307200 150M 83 Linux /dev/sda2 307512 15628030 15320519 7.3G 83 Linux

I want to make ext2 file system. I want to set "number-of-inodes " option to some number. I tried several values: - if *-N 99000* then Inode count: 99552 - if *-N 3500* then Inode count: 3904 - if *-N 500* then Inode count: 976 But always my value is **not the same**. Why? I call mkfs this way sudo mkfs -q -t ext2 -F /dev/sda2 -b 4096 -N 99000 -O none,sparse_super,large_file,filetype I check results this way $ sudo tune2fs -l /dev/sda2 tune2fs 1.46.5 (30-Dec-2021) Filesystem volume name: Last mounted on: Filesystem UUID: 11111111-2222-3333-4444-555555555555 Filesystem magic number: 0xEF53 Filesystem revision #: 1 (dynamic) Filesystem features: filetype sparse_super large_file Filesystem flags: signed_directory_hash Default mount options: user_xattr acl Filesystem state: clean Errors behavior: Continue Filesystem OS type: Linux Inode count: 99552 Block count: 1973720 Reserved block count: 98686 Overhead clusters: 6362 Free blocks: 1967353 Free inodes: 99541 First block: 0 Block size: 4096 Fragment size: 4096 Blocks per group: 32768 Fragments per group: 32768 Inodes per group: 1632 Inode blocks per group: 102 Filesystem created: Thu Apr 6 20:00:45 2023 Last mount time: n/a Last write time: Thu Apr 6 20:01:49 2023 Mount count: 0 Maximum mount count: -1 Last checked: Thu Apr 6 20:00:45 2023 Check interval: 0 () Reserved blocks uid: 0 (user root) Reserved blocks gid: 0 (group root) First inode: 11 Inode size: 256 Required extra isize: 32 Desired extra isize: 32 Default directory hash: half_md4 Directory Hash Seed: 61ff1bad-c6c8-409f-b334-f277fb29df54

I have an ext2 image file, and I need to write a file to a specific inode within the image using command line utilities in Linux. I tried using debugfs but I couldn't find a way to write to a specific inode. Can someone provide guidance on how to write a file to a specific inode on an ext2 image using command line tools? Any insights, commands, or sample scripts would be greatly appreciated.

In this [book](https://tldp.org/LDP/tlk/tlk.html) , the following is mentioned about filesystem addressing: > A file system does not need to concern itself with where on the physical media a block should be put, that is the job of the device's driver I have some questions related to this: 1. Do the pointers that are part of the inodes comprise of logical block indices or actual physical addresses? 1. If it is the former, then where is the mapping of block index to actual physical location stored? 1. Is there an example of how the physical addressing might look like, e.g. for an SSD device?

I have a task for university to deal with EXT2 file recovery. The problem is that the example drives (as IMG files) we got only contain one block group. I want to test if I read the drive correctly so I need more than one block group. I tried to create an IMG file from my Kubuntu USB drive but did not manage to do it. I searched online but found not a single IMG file to download. Google only wanted to sell some ext2 drivers to me. Where can I get an ext2 IMG file from?

I just saw [an answer question about filesystems for embedded hardware](https://raspberrypi.stackexchange.com/a/1169) on another Stack Exchange site. The question was "What file system format should I use on flash memory?" and the answer suggested the ext2 filesystem, or the ext3 filesystem with journaling disabled a'la tune2fs -O ^has_journal /dev/sdbX This made me wonder... What would the advantage be to using ext3 (with journaling disabled) over ext2? As far as I understood, the only real difference between the two was the journal. What other differences between ext2 and ext3 are there?

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?

Is it possible to install (and use) grub on the same ext2 partition as the linux root directory? (Should you want to discuss 'why': to try, to understand and master.)

I am trying to find the creation date on an _ext2_ file system. I seem to get a current date using dumpe2fs.
The problem is that the original _ext2_ superblock specification does not contain such information, though it seems like there might be an extension to the original fields (something about after byte 264).
In fact using hexdump on the superblock (hexdump -s 1024 -n 1024 -C /dev/vdb) I can find 4 bytes starting from byte _265_ that containg a hex number which contain in little endian the unix time of the file system creation. Any information on how, why and under what circumstances that it there?
Thanks in advance

I'm currently writing a hobby file-system for fun. I was wondering if anyone knows why or where I could get information on the design philosophy of ext2. Specifically, I was wondering why each inode has only 12 direct blocks? Why not 13, or 100?

I have an image (from an Android phone) for which file gave the following info: file vendor-rw.img vendor-rw.img: Linux rev 1.0 ext2 filesystem data, UUID=64d47c8e-6f74-54ea-bbe7-ce29a05c4b04, volume name "vendor" (extents) (large files) (huge files) I can successfully mount image with the following command in Ubuntu 20 x64: sudo mount -o loop,rw -t ext4 vendor-rw.img tmp/ Obviously the image is not sparse but I cannot edit the content of the mounted drive; What is the problem? **Solved**!: The owner of the mounted point was root and I was running operations on the drive (mkdir for example) as non-root user.

using dumpe2fs on some ext4 partition, I get in the initial data, that the first inode is #11. However, if I ls -i on this disk root partition, I get that it's inode number is #2 (as expected). So... What is this “first partition” reported by dumpe2fs ?

What I'm trying achieve is, a safe shrinking of an ext2 file system and make sure I can cut/shrink the physical partition underneath to a safe minimum (without cutting file system blocks). I have checked many HowTo-s, but still want to ask if I'm missing something, when determining the actual ext2 usage as reported by dumpe2fs. Here is my test case: root@buster:/tmp# dd if=/dev/zero of=/tmp/del.img bs=1M count=1000 1000+0 records in 1000+0 records out 1048576000 bytes (1.0 GB, 1000 MiB) copied, 0.429782 s, 2.4 GB/s root@buster:/tmp# losetup -f --show /tmp/del.img /dev/loop0 root@buster:/tmp# mkfs.ext2 /dev/loop0 mke2fs 1.44.5 (15-Dec-2018) Discarding device blocks: done Creating filesystem with 256000 4k blocks and 64000 inodes Filesystem UUID: 217a401a-a001-46e8-8ca2-9602e927e2aa Superblock backups stored on blocks: 32768, 98304, 163840, 229376 Allocating group tables: done Writing inode tables: done Writing superblocks and filesystem accounting information: done root@buster:/tmp# mount /dev/loop0 /mnt/EXT2/ root@buster:/tmp# dumpe2fs /dev/loop0 | grep -E '(Block count|Block size)' dumpe2fs 1.44.5 (15-Dec-2018) Block count: 256000 Block size: 4096 As I see it, the filesystem uses 1048576000 bytes (256000*4096) root@buster:/tmp# cp -pr /opt/Scripts/ /mnt/EXT2/ root@buster:/tmp# umount /mnt/EXT2 root@buster:/tmp# e2fsck -f /dev/loop0 e2fsck 1.44.5 (15-Dec-2018) Pass 1: Checking inodes, blocks, and sizes Pass 2: Checking directory structure Pass 3: Checking directory connectivity Pass 4: Checking reference counts Pass 5: Checking group summary information /dev/loop0: 457/64000 files (6.6% non-contiguous), 67098/256000 blocks root@buster:/tmp# resize2fs -M /dev/loop0 resize2fs 1.44.5 (15-Dec-2018) Resizing the filesystem on /dev/loop0 to 63894 (4k) blocks. The filesystem on /dev/loop0 is now 63894 (4k) blocks long. root@buster:/tmp# dumpe2fs /dev/loop0 | grep -E '(Block count|Block size)' dumpe2fs 1.44.5 (15-Dec-2018) Block count: 63894 Block size: 4096 After shrinking, the filesystem seems to be using 261709824 bytes (63894*4096) May I assume than in 100% of the cases, I can safely cut/shrink the underlying physical partition to these 261709824 bytes as well? Could it be that some filesystem blocks are still physically located after these 261709824 bytes?

On an ext3 (or ext2/4, pick your flavor) filesystem, how would one extract raw byte data that corresponds to a particular inode directly from the hard drive? Is it possible given, say, an inode number to determine its location on disk (perhaps as an offset from the start of the partition, or some other LBA offset) and then use some utility such as dd or a system call (something like lseek except operating on the filesystem?) to read that data without having to reference it as a file? I'm assuming this can be done, perhaps with some sort of driver-level utility.

In every publication I found about ext2, the structure of a block group is defined as following: - Super Block: 1 block - Group Descriptor: N blocks - Data Bitmap: 1 block - Inode Bitmap: 1 block - Inode Table: N blocks - Data Blocks: remaining blocks However in the ext2 kernel doc it is stated that versions >0 may not store copies of the super block and group descriptors in every block group. When I fsstat my ext2 partition, I get following output: Group: 1: Inode Range: 1977 - 3952 Block Range: 8193 - 16384 Layout: Super Block: 8193 - 8193 Group Descriptor Table: 8194 - 8194 Data bitmap: 8451 - 8451 Inode bitmap: 8452 - 8452 Inode Table: 8453 - 8699 Data Blocks: 8700 - 16384 Free Inodes: 1976 (100%) Free Blocks: 0 (0%) Total Directories: 0 Group: 2: Inode Range: 3953 - 5928 Block Range: 16385 - 24576 Layout: Data bitmap: 16385 - 16385 Inode bitmap: 16386 - 16386 Inode Table: 16387 - 16633 Data Blocks: 16387 - 16386, 16634 - 24576 Free Inodes: 1976 (100%) Free Blocks: 0 (0%) There are two things about this output that confuse me: 1. In groups where the SB and group desc. are stored, there is a gap of 256 blocks between the group desc. and data bitmap. **EDIT: Using dumpe2fs I just found out that these are reserved GDT blocks, used for online resizing .** So the new question is, how is the size of these reserved GDT blocks determined? 2. What does Data Blocks: 16387 - 16386 in Group 2 mean?

I study the ext2_sb_info structure (the memory data structure for ext2 superblock) and i noticed the existence of a field declared as u32 s_next_generation; I searched the web but it was not possible to find its role. Does anyone knows what is the purpose of this field? Thanks a lot!