Resolve growpart failures when extending GPT partitions -

Symptoms

A cloud disk is formatted with a GPT partition. After a cloud disk extension, using the growpart utility to extend a partition, such as /dev/vdb1, returns an error message similar to the following. As a result, the cloud disk capacity increases, but the available space on the partition and its file system does not increase. This topic uses the /dev/vdb1 partition as an example.

[root@ixxx ~]# growpart /dev/vdb 1
failed [pt_update:1] pt_update /dev/vdb 1
partx: /dev/vdb: error updating partition 1
FAILED: disk=/dev/vdb partition=1: failed to repartition
***** WARNING: Resize failed, attempting to revert ******
Warning: The kernel is still using the old partition table.
The new table will be used at the next reboot.
The operation has completed successfully.
***** Appears to have gone OK ****

Cause

This issue occurs because the data disk, such as /dev/vdb, lacks the recommended partition alignment. Specifically, the mkpart primary 1 100% command was not run to set the start and end positions of the partition.

You can run the following commands to check whether the partition is aligned:

fdisk -l: Check the Start value. If the value is not 2048, the partition is not aligned.

parted -l: Check the Start value. If the value is not 1049 kB, as shown in the following example output, the partition is not aligned.

[root@izxxx ~]# parted -l
Model: Virtio Block Device (virtblk)
Disk /dev/vda: 42.9GB
Sector size (logical/physical): 512B/512B
Partition Table: gpt
Disk Flags:
Number  Start   End     Size    File system  Name                  Flags
 1      1049kB  101MB   99.6MB  fat16        EFI System Partition  boot
 2      101MB   20.1GB  20.0GB  ext4
Model: Virtio Block Device (virtblk)
Disk /dev/vdb: 3221GB
Sector size (logical/physical): 512B/512B
Partition Table: gpt
Disk Flags:
Number  Start   End     Size    File system  Name     Flags
 1      17.4kB  1074GB  1074GB  ext4         primary

Solution

To resolve this issue, you must repartition the disk and then extend the partition. Follow these steps:

Connect to the ECS instance remotely.

For more information, see Connection method overview.

Run the following command to view the partition information for /dev/vdb1 in the /etc/fstab file.

cat /etc/fstab

For example, the information for the /dev/vdb1 partition is as follows.

[root@iZxxx ~]# cat /etc/fstab
#
# /etc/fstab
# Created by anaconda on Fri Mar 18 11:23:53 2022
#
# Accessible filesystems, by reference, are maintained under '/dev/disk'
# See man pages fstab(5), findfs(8), mount(8) and/or blkid(8) for more info
#
UUID=1ecad39c-b7f6-4d5f-bfe1-2ffec1877a1d /                       ext4    defaults        1 1
UUID=B483-4E9C          /boot/efi               vfat    umask=0077,shortname=winnt 0 0
UUID=f315122e-2d1d-4705-aaaa-1ad62ae66096 /mnt ext4 defaults 0 0

Run the following command to edit the etc/fstab file, and then manually delete the partition information for /dev/vdb1.
```
vim /etc/fstab
```

Run the following command to unmount the /dev/vdb1 partition.

umount /dev/vdb1

[root@xxx          ~]# df -h
Filesystem      Size  Used Avail Use% Mounted on
devtmpfs         31G     0   31G   0% /dev
tmpfs            31G     0   31G   0% /dev/shm
tmpfs            31G   33M   31G   1% /run
tmpfs            31G     0   31G   0% /sys/fs/cgroup
/dev/vda2        19G  3.5G   14G  21% /
/dev/vda1        95M   12M   84M  12% /boot/efi
tmpfs           6.2G     0  6.2G   0% /run/user/0
/dev/vdb1       985G   77M  935G   1% /mnt
[root@xxx          ~]# umount /dev/vdb1
[root@xxx          ~]# df -h
Filesystem      Size  Used Avail Use% Mounted on
devtmpfs         31G     0   31G   0% /dev
tmpfs            31G     0   31G   0% /dev/shm
tmpfs            31G   33M   31G   1% /run
tmpfs            31G     0   31G   0% /sys/fs/cgroup
/dev/vda2        19G  3.5G   14G  21% /
/dev/vda1        95M   12M   84M  12% /boot/efi
tmpfs           6.2G     0  6.2G   0% /run/user/0

Repartition the disk and mount the file system.

Important
Repartitioning the disk deletes all data on the original partition. Before you proceed, create a snapshot to back up all data on the cloud disk. After you repartition the disk and mount the new file system, you can use the backup data to restore the original data. For more information about how to create a snapshot, see Create a snapshot for a disk.

For more information, see Initialize a data disk on a Linux instance.
Extend the partition and file system again. For instructions, see Extend partitions and file systems (Linux).