lsblk - List block device information.

Lsblk is a linux utility to list block device information. In this blog post, I’ll cover some useful lsblk commands.

To see list of devices :

[root@sandbox ~]# lsblk
NAME                          MAJ:MIN RM  SIZE RO TYPE MOUNTPOINT
sda                             8:0    0 48.8G  0 disk
|-sda1                          8:1    0  500M  0 part /boot
`-sda2                          8:2    0 48.3G  0 part
  |-vg_sandbox-lv_root (dm-0) 253:0    0 43.5G  0 lvm  /
  `-vg_sandbox-lv_swap (dm-1) 253:1    0  4.9G  0 lvm  [SWAP]

By default lsblk prints information in tree view, if you want to see information in list view, you can use -l option.

[root@sandbox ~]# lsblk -l
NAME                      MAJ:MIN RM  SIZE RO TYPE MOUNTPOINT
sda                         8:0    0 48.8G  0 disk
sda1                        8:1    0  500M  0 part /boot
sda2                        8:2    0 48.3G  0 part
vg_sandbox-lv_root (dm-0) 253:0    0 43.5G  0 lvm  /
vg_sandbox-lv_swap (dm-1) 253:1    0  4.9G  0 lvm  [SWAP]

Here,

• NAME is name of device ,
• MAJ:MIN is major:minor version of device
• RM tells that its a removal device
• SIZE is size of device in human readable format
• RO tells that its Read Only device
• TYPE is device type
• MOUNTPOINT is location where device is mounted.

To see device size in bytes

[root@sandbox ~]# lsblk -b
NAME                          MAJ:MIN RM        SIZE RO TYPE MOUNTPOINT
sda                             8:0    0 52428800000  0 disk
|-sda1                          8:1    0   524288000  0 part /boot
`-sda2                          8:2    0 51903463424  0 part
  |-vg_sandbox-lv_root (dm-0) 253:0    0 46657437696  0 lvm  /
  `-vg_sandbox-lv_swap (dm-1) 253:1    0  5242880000  0 lvm  [SWAP]

To see filesystem information

[root@sandbox ~]# lsblk -fl
NAME                      FSTYPE      LABEL UUID                                   MOUNTPOINT
sda
sda1                      ext4              8ed32b8c-b23a-423b-b96f-29eaa1303ae1   /boot
sda2                      LVM2_member       6CXjrD-6st6-olYP-BQAK-psA0-dS3T-8KeIRU
vg_sandbox-lv_root (dm-0) ext4              d6e7730a-608a-4e67-8814-131e23411619   /
vg_sandbox-lv_swap (dm-1) swap              dc07cc2c-1b35-4b06-a52b-c0d162669afe   [SWAP]

Here

• FSTYPE is filesystem type
• LABEL is filesystem label
• UUID is filesystem UUID

To see device permissions

[root@sandbox ~]# lsblk -m
NAME                           SIZE OWNER GROUP MODE
sda                           48.8G root  disk  brw-rw----
|-sda1                         500M root  disk  brw-rw----
`-sda2                        48.3G root  disk  brw-rw----
  |-vg_sandbox-lv_root (dm-0) 43.5G root  disk  brw-rw----
  `-vg_sandbox-lv_swap (dm-1)  4.9G root  disk  brw-rw----

Here,

• OWNER is user who created this device
• GROUP is group name to which user belongs
• MODE is device permissions

To see device topology information

[root@sandbox ~]# lsblk -tl
NAME                      ALIGNMENT MIN-IO OPT-IO PHY-SEC LOG-SEC ROTA SCHED RQ-SIZE   RA
sda                               0    512      0     512     512    1 cfq       128  128
sda1                              0    512      0     512     512    1 cfq       128  128
sda2                              0    512      0     512     512    1 cfq       128  128
vg_sandbox-lv_root (dm-0)         0    512      0     512     512    1           128  128
vg_sandbox-lv_swap (dm-1)         0    512      0     512     512    1           128  128

Here,

• ALIGNMENT is alignment offset of device
• MIN-IO is minimum I/O size
• OPT-IO is optimal I/O size
• PHY-SEC is physical sector size
• LOG-SEC is logical sector size
• ROTA tells that its a rotational device
• SCHED is name of I/O scheduler
• RQ-SIZE is size of request queue
• RA is read ahead of device.