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:

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)

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