Universally unique identifier (UUID)

Universally unique identifier (UUID)

• Filesystem UUID
• Block device UUID: lsblk -io KNAME,TYPE,SIZE,MODEL,UUID
• LVM PV UUID: pvdisplay

• blkid -s UUID -o value /dev/vdb1655

• uuid=`findmnt /mnt/your_path -o UUID -n`

EXT4 filesystem

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

LVM

pvdisplay

 --- Physical volume ---
 PV Name               /dev/sdc3
 VG Name               rhvh
 PV Size               <7.28 TiB / not usable 3.00 MiB
 Allocatable           yes
 PE Size               4.00 MiB
 Total PE              1907390
 Free PE               25600
 Allocated PE          1881790
 PV UUID               Tk3lEU-NzHl-miXe-bKNk-wcNN-vvou-nM0IGD

pvcreate --uuid "FmGRh3-zhok-iVI8-7qTD-S5BI-MAEN-NYM5Sk" --restorefile /etc/lvm/archive/VG_00050.vg /dev/sdh1
  Physical volume "/dev/sdh1" successfully created

pvchange --uuid Generate new random UUID for specified PVs.

Related terms

• https://datatracker.ietf.org/doc/html/draft-peabody-dispatch-new-uuid-format-04#name-uuid-version-7
• /etc/fstab
• uuid node.js module
• uuidgen
• Kubernetes UID
• Elasticsearch index: curl -k "https://localhost:9200/_cat/indices?v&health=red" -u'XXX:UUU'
• ULID

See also

• File systems: mount, umount, findmnt, find, swapon, swapoff, UUID, blkid, mount options: /etc/fstab, udisksctl mount, guestmount, /proc/mounts, fstrim, systemd-mount, defaults
• File systems: clustered file system, tune2fs mkfs.ext4,superblock, e2fsck, resize2fs, mount, df, umount, UUID, fstab
• File systems: ext4, XFS, ZFS, btrfs, wipefs, findfs, HDFS, overlay, aufs, virt-filesystems, Windows: (FAT, NTFS, ReFS), GPFS, squashfs, Ecryptfs, Encfs, FUSE, VMFS, Comparison of distributed file systems, Userspace filesystem, Resize filesystem size
• PV: pvcreate, pvchange
• libuuid provided by util-linux package
• multipath, multipathd, mpathpersist, WWIDS, /etc/multipath.conf
• PTUUID and PARTUUID
• UUID, uuidgen, uuid-ossp (PostgreSQL), ULID