Here you can see how to online resize your root ext4 file system. The free space of your partition will be increased after the operation. The size of the root file system will grow not shrink. Of course, this could have been any other partition, not exactly the root one, but in most cases, such operations on the root are the more complex and dangerous – SO ALWAYS do backups before such operations!
All services work properly and no shut down of services, no reboot, or umount is required during the resize operation.
Still, we rebooted the server once to force check the file system as a precaution, because it was possible and this server was not in production. The reboot of the server after this kind of resizing is not mandatory.
The following method is tested on CentOS 7, Ubuntu 16 LTS, and Gentoo with kernel 4.15 kernel. So we can assume you may have no problems if your system is newer than ours.
- Partition resize – Use resizepart in parted command. All Linux distributions have this package with the same name as the needed command “parted”
- File system resize – Use resize2fs from the E2fsprogs package. All Linux distributions include this package mostly with the same name of the package.
STEP 1) Expand the partition, which holds the root partition.
Let’s assume you have changed your disk and now there is more unallocated space to be used or somehow the space of the disk is increased. Look below for a real-world example with one of our virtual servers.
root@srv1 ~ # parted /dev/sda GNU Parted 3.2 Using /dev/sda Welcome to GNU Parted! Type 'help' to view a list of commands. (parted) p Model: Model: ATA Samsung SSD 850 (scsi) Disk /dev/sda: 215GB Sector size (logical/physical): 512B/512B Partition Table: gpt Disk Flags: Number Start End Size File system Name Flags 1 1049kB 2097kB 1049kB bios_grub 2 2097kB 4096MB 4094MB linux-swap(v1) 3 4096MB 24.0GB 19.9GB ext4 (parted) resizepart 3 -1 Warning: Partition /dev/sda3 is being used. Are you sure you want to continue? parted: invalid token: -1 Yes/No? Yes End? [24.0GB]? -1 (parted) p Model: Model: ATA Samsung SSD 850 (scsi) Disk /dev/sda: 215GB Sector size (logical/physical): 512B/512B Partition Table: gpt Disk Flags: Number Start End Size File system Name Flags 1 1049kB 2097kB 1049kB bios_grub 2 2097kB 4096MB 4094MB linux-swap(v1) 3 4096MB 215GB 211GB ext4 (parted) q Information: You may need to update /etc/fstab.
As you can see from the first print command the partition number 3 is 19.9GB and after the resize command with “-1” is 211GB. There is a warning about the partition is used, but it is normal and not critical.
STEP 2) Resize the file system, on which we expanded the partition.
You need to install E2fsprogs. All Linux distributions have this package, here are some of them:
- CentOS 7 – e2fsprogs
- Ubuntu – e2fsprogs
- Gentoo – sys-fs/e2fsprogs
After installing the e2fsprogs package you will have the online ext4 resizing tool – resize2fs.
root@srv ~ # resize2fs /dev/sda3 resize2fs 1.42.13 (17-May-2015) Filesystem at /dev/sda3 is mounted on /; on-line resizing required old_desc_blocks = 2, new_desc_blocks = 13 The filesystem on /dev/sda3 is now 51428620 (4k) blocks long.
Check if everything is OK with
root@srv ~ # dmesg|grep EXT4 [ 449.330140] EXT4-fs (vda3): resizing filesystem from 4859392 to 51428620 blocks [ 449.936044] EXT4-fs (vda3): resized filesystem to 51428620 root@srv ~ # df -h Filesystem Size Used Avail Use% Mounted on udev 3.9G 0 3.9G 0% /dev tmpfs 798M 3.5M 795M 1% /run /dev/sda3 193G 3.4G 182G 2% / tmpfs 3.9G 0 3.9G 0% /dev/shm tmpfs 5.0M 0 5.0M 0% /run/lock tmpfs 3.9G 0 3.9G 0% /sys/fs/cgroup tmpfs 798M 0 798M 0% /run/user/0
Bonus – you can force check the file system on the next reboot
Probably it is a good idea to force check the file system integrity on the next boot. This step is not mandatory and you may skip it.
For Ubuntu you can do:
root@srv ~ # touch /forcefsck root@srv ~ # reboot
Fixing the GPT. Newer versions may display warning the GPT table is not using the whole disk space and to fix it. Just type fix to add the new unallocated disk space:
root@srv ~ # parted /dev/sda GNU Parted 3.2 Using /dev/sda Welcome to GNU Parted! Type 'help' to view a list of commands. (parted) p Warning: Not all of the space available to /dev/sda appears to be used, you can fix the GPT to use all of the space (an extra 188743680 blocks) or continue with the current setting? Fix/Ignore? Fix Model: Virtio Block Device (virtblk) Disk /dev/sda: 118GB Sector size (logical/physical): 512B/512B Partition Table: gpt Disk Flags: Number Start End Size File system Name Flags 1 1049kB 2097kB 1049kB bios_grub 2 2097kB 17.2GB 17.2GB ext4 3 17.2GB 21.5GB 4293MB linux-swap(v1) (parted)