How To : Extend ext4 partition Linux (Centos 7)

April 22, 2019 Linux

WARNING ! BEFORE PROCEED, THIS GUIDE IS ONLY FOR NEWLY PROVISIONED LINUX VM, ANY LIVE ENVIRONMENT REQUIRE DIFFERENT SET OF STEPS

Once you have provision a Linux VM from a template and configured the network.

The default partition size for the VM is : 16 GB

[root@centos7 ~]# df -h
 Filesystem      Size  Used Avail Use% Mounted on
 /dev/sda1        16G  1.7G   14G  12% /
 devtmpfs        909M     0  909M   0% /dev
 tmpfs           920M     0  920M   0% /dev/shm
 tmpfs           920M  8.8M  911M   1% /run
 tmpfs           920M     0  920M   0% /sys/fs/cgroup
 tmpfs           184M     0  184M   0% /run/user/0
 [root@centos7 ~]#

Customer should have their own required HDD size, and you should make sure you have changed it on the VM settings.

For this guide, the customer would want 200GB for their VM.

Enter the partitioning tools fdisk :

[root@centos7 ~]# fdisk /dev/sda
 Welcome to fdisk (util-linux 2.23.2).
 Changes will remain in memory only, until you decide to write them.
 Be careful before using the write command.


Command (m for help):

use p to print the current partition :

Command (m for help): p
 Disk /dev/sda: 214.7 GB, 214748364800 bytes, 419430400 sectors
 Units = sectors of 1 * 512 = 512 bytes
 Sector size (logical/physical): 512 bytes / 512 bytes
 I/O size (minimum/optimal): 512 bytes / 512 bytes
 Disk label type: dos
 Disk identifier: 0x000a25aa
 Device Boot      Start         End      Blocks   Id  System
 /dev/sda1   *        2048    33554431    16776192   83  Linux

use d to delete the current partition :

Command (m for help): d
 Selected partition 1
 Partition 1 is deleted

use n to create a new partition and follow as below :

Command (m for help): n
 Partition type:
    p   primary (0 primary, 0 extended, 4 free)
    e   extended
 Select (default p): p
 Partition number (1-4, default 1):
 First sector (2048-419430399, default 2048):
 Using default value 2048
 Last sector, +sectors or +size{K,M,G} (2048-419430399, default 419430399):
 Using default value 419430399
 Partition 1 of type Linux and of size 200 GiB is set

use w to write/save the partition :

Command (m for help): w
 The partition table has been altered!
 Calling ioctl() to re-read partition table.
 WARNING: Re-reading the partition table failed with error 16: Device or resource busy.
 The kernel still uses the old table. The new table will be used at
 the next reboot or after you run partprobe(8) or kpartx(8)
 Syncing disks.

Once we have resize the partition, we need to either reboot or run below command to make sure it take effect before resizing the file system.

[root@centos7 ~]# partprobe /dev/sda

Once done, run below command to resize the filesystem to follow the new partition size.

[root@centos7 ~]# resize2fs /dev/sda1
 resize2fs 1.42.9 (28-Dec-2013)
 Filesystem at /dev/sda1 is mounted on /; on-line resizing required
 old_desc_blocks = 2, new_desc_blocks = 25
 The filesystem on /dev/sda1 is now 52428544 blocks long.
 [root@centos7 ~]#

run df -h to double check whether it is successfully.

[root@centos7 ~]# df -h
 Filesystem      Size  Used Avail Use% Mounted on
 /dev/sda1       197G  1.7G  187G   1% /
 devtmpfs        909M     0  909M   0% /dev
 tmpfs           920M     0  920M   0% /dev/shm
 tmpfs           920M  8.8M  911M   1% /run
 tmpfs           920M     0  920M   0% /sys/fs/cgroup
 tmpfs           184M     0  184M   0% /run/user/0
 [root@centos7 ~]#

As we can see above we successfully resize the partition for root partition.

To double confirm everything is okay, run reboot command :

init 6

If the VM boot fine after reboot, and the new size is there. You can proceed any other task for the VM.

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