Mkfs.ext4

• Man page: https://linux.die.net/man/8/mkfs.ext4

mkfs.ext4 /dev/vg01/lv01
mke2fs 1.44.1 (24-Mar-2018)
Creating filesystem with 2441850880 4k blocks and 305233920 inodes
Filesystem UUID: e6742357-a181-4b82-837f-9a01f3e52568
Superblock backups stored on blocks:
	32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632, 2654208,
	4096000, 7962624, 11239424, 20480000, 23887872, 71663616, 78675968,
	102400000, 214990848, 512000000, 550731776, 644972544, 1934917632

Allocating group tables: done
Writing inode tables: done
Creating journal (262144 blocks): done
Writing superblocks and filesystem accounting information: done

mkfs.ext4 /dev/sda222
mke2fs 1.44.1 (24-Mar-2018)
Found a dos partition table in /dev/sda222
Proceed anyway? (y,N) y
mkfs.ext4: inode_size (128) * inodes_count (0) too big for a filesystem with 0 blocks, specify higher inode_ratio (-i) or lower inode count (-N).

Review your partition table (fdisk -l /dev/sda222), read https://www.beinfog.com/systems/dont-try-to-create-file-system-on-an-extended-partition/

mkfs.ext4 -S
-S  Write superblock and group descriptors only.

Create an ext4 filesystem on a file:

fallocate -l 1G  /path/to/yourfile
mkfs.ext4 -F /path/to/yourfile
-F force mke2fs to create a filesystem, even if the specified device is not a partition on a block special device, or if other parameters do not make sense. In order to force mke2fs to create a filesystem even if the filesystem appears to be in use or is mounted (a truly dangerous thing to do), this option must be specified twice. (from man page)
sudo mount /path/to/yourfile /mnt/directory_to_mount
df -h /mnt/directory_to_mount

Activities

1. Create an ext4 filesystem using mkfs.ext4 command
2. Learn about bytes per inode ratio: https://wiki.archlinux.org/index.php/ext4#Bytes-per-inode_ratio
3. resize2fs online and ext4 filesystem
4. Learn about Lazy initialization feature of ext4: https://www.thomas-krenn.com/en/wiki/Ext4_Filesystem#Lazy_Initialization and how to avoid it mkfs.ext4 -E lazy_itable_init=0,lazy_journal_init=0 /dev/mapper/fc-device

See also

• File systems: clustered file system, tune2fs mkfs.ext4,superblock, e2fsck, resize2fs, mount, df, umount, UUID, fstab
• ext4 e2fsck, fsck.ext4, superblock, inode, block size, mkfs.ext4 tune2fs, wipefs, resize2fs stat, extents, Review ext4 journalctl logs. Read-only file system, virt-resize, ACL
• mount (/etc/fstab)
• mkfs, mkfs.ext4, mkfs -t, mount
• LVM: LVM errors LVM scan commands lkvmetad, Add a new disk

scan: pvscan vgscan

LVM: lvs lvmscan lvm fullreport lvmreport lvmconfig lvmdump lvmcheck lvm dumpconfig

Scan: pvs vgs lvs pvscan vgscan

PV: pvcreate pvremove pvscan pvremove pvscan pvs pvchange pvck pvdisplay pvresize

LV: lvdisplay lvcreate lvremove, lvresize, lvextend, lvreduce, lvrename

VG: vgdisplay,vgcreate,vgremove, vgextend, vgreduce, vgscan, vgchange, vgrename, vgcfgbackup, vgcfgrestore, vgimportclone, vgck

Check commands: pvck vgck

• inode, superblock and block size