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    Alibaba Cloud Linux:How do I handle errors that occur when I resize Ext4 file systems?

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    Alibaba Cloud Linux:How do I handle errors that occur when I resize Ext4 file systems?

    Last Updated:Dec 06, 2024

    Ext4 is a file system that is widely used. You can extend Ext4 file systems online and extend or shrink Ext4 file systems offline based on your storage requirements. However, you may encounter errors when you extend Ext4 file systems. This topic describes how to identify and handle the errors to ensure that the Ext4 file systems can be extended. In the examples, the /dev/vdb disk is used.

    resize2fs: Bad magic number in super-block while trying to open /dev/vdb

    Problem description

    You run the following resize2fs command: 

    sudo resize2fs /dev/vdb

    The following error messages appear:

    resize2fs: Bad magic number in super-block while trying to open /dev/vdb
Couldn't find valid filesystem superblock.

    Cause

    The device that you want to extend, such as /dev/vdb, is not formatted to Ext4.

    Solution

    Check the file systems on the device. Make sure that the file systems on the device are Ext4 file systems. 

    lsblk --fs /dev/vdb

    resize2fs: Device or resource busy while trying to open /dev/vdb

    Problem description

    You run the following resize2fs command: 

    sudo resize2fs /dev/vdb

    The following error messages appear:

    resize2fs: Device or resource busy while trying to open /dev/vdb
Couldn't find valid filesystem superblock.

    Cause

    In most cases, the preceding issue occurs because the file system that you want to extend resides on a partition. For example, when you run the resize2fs command with the disk name /dev/vdb as an argument but the file system actually resides at /dev/vdb1 partition, the preceding error messages appear. 

    NAME   MAJ:MIN RM  SIZE RO TYPE MOUNTPOINT
vdb    253:16   0  100G  0 disk
└─vdb1 253:17   0   50G  0 part

    Solution

    1. Extend the partition. 

    sudo growpart /dev/vdb 1

    The following command output indicates that the partition is extended:

    CHANGED: partition=1 start=2048 old: size=104855552 end=104857599 new: size=209713119 end=209715166

    1. Extend the file system. 

    sudo resize2fs /dev/vdb1

    The following command output indicates that the file system is extended:

    resize2fs 1.46.0 (29-Jan-2020)
Filesystem at /dev/vdb1 is mounted on /mnt/test; on-line resizing required
old_desc_blocks = 7, new_desc_blocks = 13
The filesystem on /dev/vdb1 is now 26214139 (4k) blocks long.

    The filesystem is already 13106944 (4k) blocks long. Nothing to do!

    Problem description

    You run the following resize2fs command: 

    sudo resize2fs /dev/vdb1

    The following error message appears:

    The filesystem is already 13106944 (4k) blocks long.  Nothing to do!

    Cause

    In most cases, the preceding issue occurs because the file system that you want to extend resides on a partition. For example, when you run the resize2fs command with the partition name /dev/vdb1 as an argument, the preceding error message appears. 

    NAME   MAJ:MIN RM  SIZE RO TYPE MOUNTPOINT
vdb    253:16   0  100G  0 disk
└─vdb1 253:17   0   50G  0 part

    Solution

    1. Extend the partition. 

    sudo growpart /dev/vdb 1

    The following command output indicates that the partition is extended:

    CHANGED: partition=1 start=2048 old: size=104855552 end=104857599 new: size=209713119 end=209715166

    1. Extend the file system. 

    sudo resize2fs /dev/vdb1

    The following command output indicates that the file system is extended:

    resize2fs 1.46.0 (29-Jan-2020)
Filesystem at /dev/vdb1 is mounted on /mnt/test; on-line resizing required
old_desc_blocks = 7, new_desc_blocks = 13
The filesystem on /dev/vdb1 is now 26214139 (4k) blocks long.

    resize2fs: On-line shrinking not supported

    Problem description

    You run the following resize2fs command: 

    sudo resize2fs /dev/vdb

    The following error messages appear:

    Filesystem at /dev/vdb is mounted on /mnt/test; on-line resizing required
resize2fs: On-line shrinking not supported

    Cause

    Ext4 file systems can be shrunk offline but cannot be shrunk online.

    Solution

    1. Check whether the device is mounted. 

    mount | grep /dev/vdb

    1. Unmount the file system. 

    sudo umount /mnt/test

    1. Run the resize2fs command to extend the file system. 

    sudo resize2fs /dev/vdb 50G

    The following command output indicates that the file system is shrunk:

    Resizing the filesystem on /dev/vdb to 13107200 (4k) blocks.
The filesystem on /dev/vdb is now 13107200 (4k) blocks long.

    resize2fs: Permission denied to resize filesystem

    Problem description

    You run the following resize2fs command: 

     resize2fs /dev/vdb

    The following error message appears:

    resize2fs: Permission denied to resize filesystem

    Cause

    The CAP_SYS_RESOURCE privilege is required to perform resize2fs operations, or the file system contains errors.

    Solution

    1. Run the resize2fs command with sudo privileges. 

    sudo resize2fs /dev/vdb

    1. If the issue persists, check the file system for errors. 

    dmesg | grep "EXT4-fs"

    1. If the file system contains errors, unmount the file system and perform a file system check (fsck). 

    sudo umount /mnt/test
sudo fsck -y /dev/vdb

    1. Run the resize2fs command to extend the file system offline. 

    sudo resize2fs /dev/vdb