How to Expand an Unpartitioned Data Disk on CentOS 7.4

When a data disk has no partitions and only a filesystem is created (or the disk is formatted), it can be mounted directly. # lsblk shows sdb has no partitions The example uses CentOS 7.4 64‑bit, where /dev/sdb originally 5 GB without partitions, later expanded to 10 GB in the console. The guide shows how to enlarge the filesystem to use the added space.

Extend ext* filesystem

Run resize2fs on the disk: resize2fs /dev/sdb

# lsblk
NAME            MAJ:MIN RM  SIZE RO TYPE MOUNTPOINT
sda               8:0    0   20G  0 disk 
├─sda1            8:1    0    1G  0 part /boot
└─sda2            8:2    0   19G  0 part 
  ├─centos-root 253:0    0   17G  0 lvm  /
  └─centos-swap 253:1    0    2G  0 lvm  [SWAP]
sdb               8:16   0   10G  0 disk /data
sr0              11:0    1  9.5G  0 rom
# resize2fs /dev/sdb
resize2fs 1.42.9 (28-Dec-2013)
Filesystem at /dev/sdb is mounted on /data; on-line resizing required
old_desc_blocks = 1, new_desc_blocks = 2
The filesystem on /dev/sdb is now 2621440 blocks long.

Check the result with df -TH :

# df -Th
Filesystem              Type      Size  Used Avail Use% Mounted on
devtmpfs                devtmpfs  475M     0  475M   0% /dev
tmpfs                   tmpfs     487M     0  487M   0% /dev/shm
tmpfs                   tmpfs     487M  7.7M  479M   2% /run
tmpfs                   tmpfs     487M     0  487M   0% /sys/fs/cgroup
/dev/mapper/centos-root xfs        17G  1.7G   16G  10% /
/dev/sda1               xfs      1014M  138M  877M  14% /boot
/dev/sdb                ext4      9.8G   23M  9.3G   1% /data
tmpfs                   tmpfs      98M     0   98M   0% /run/user/0

Extend XFS filesystem

Run xfs_growfs on the disk:

# xfs_growfs /dev/vdb
meta-data=/dev/vdb               isize=512     agcount=4, agsize=655360 blks
         =                       sectsz=512    attr=2, projid32bit=1
         =                       crc=1         finobt=0, spinodes=0
data     =                       bsize=4096    blocks=2621440, imaxpct=25
         =                       sunit=0       swidth=0 blks
naming   =version2               bsize=4096    ascii-ci=0 ftype=1
log      =internal               bsize=4096    blocks=2560, version=2
         =                       sectsz=512    sunit=0 blks, lazy-count=1
realtime =none                   extsz=4096    blocks=0, rtextents=0
data blocks changed from 2621440 to 15728640.

Verify with df -TH :

# df -TH
Filesystem     Type      Size  Used Avail Use% Mounted on
/dev/vdb       xfs        60G   34M   60G   1% /mnt/sdc