Resize disks online for Linux instances

Step 1: Create a snapshot

Create a snapshot for the disk to back up the disk data before you resize the disk.

1. Log on to the ECS console.
2. In the left-side navigation pane, choose Instances & Images > Instances.
3. In the top navigation bar, select a region.
4. Find the instance whose disk you want to resize, and click the instance ID.
5. On the Instance Details page, click the Cloud Disk tab.
6. Find the disk that you want to resize, and click Create Snapshot in the Actions column.
7. In the dialog box that appears, enter a snapshot name, select tags from the drop-down list, and then click Create.
8. Click the Snapshot tab to view the snapshot.
   When 100% appears in the Progress column corresponding to the snapshot, the snapshot is created. You can continue to perform subsequent operations.

Step 2: Resize the disk in the ECS console

1. On the Instance Details page, click the Cloud Disk tab.
2. Find the disk that you want to resize and choose More > Resize Disk in the Actions column.

   To batch resize disks, log on to the ECS console by using your Alibaba Cloud account and choose Storage & Snapshots > Disks in the left-side navigation pane. On the Disks page, select the disks that you want to resize and click Resize Disk in the lower part of the page. Disks that are attached to the same instance cannot be batch resized.

3. On the Resize Disks page, select Online Resizing, and set the Size after Resize parameter.
   The specified Size after Resize value must not be less than the current capacity.
4. Verify the price. Read and select ECS Service Terms, and then click Confirm.
5. Read the notes, click I have read the notes. Resize, and then complete the payment.

Step 3: View the disk partitions

Log on to the ECS instance to view the partition types (MBR and GPT) and file system types (such as ext4 and xfs) of the system disk and data disks. Subsequent resizing operations vary based on the types of the partitions and file systems.

1. Connect to the ECS instance. For more information, see Connect to a Linux instance by using password authentication.
2. Run the following command to view the disks attached to the instance:

   fdisk -lu

   The following figure shows a partition of the system disk (/dev/vda1) and two partitions of data disks (/dev/vdb1 and /dev/vdc1).

   No.	Partition	Description
   ①	/dev/vda1	A partition of the system disk. A value of Linux for System indicates that the partition is in the MBR format.
   ②	/dev/vdb1	A partition of a data disk. A value of Linux for System indicates that the partition is in the MBR format.
   ③	/dev/vdc1	A partition of a data disk. A value of GPT for System indicates that the partition is in the GPT format.

   Note If the disk capacity is still 40 GiB in the queried result (that is Disk /dev/vda: 42.9 GB in the figure), the resize fails. We recommend that you restart the instance in the console.
3. Run the following command to check the file system types of the existing partitions:

   df -Th

   An output similar to the following one is displayed.

   

Step 4: Resize partitions

When you view the disk partitions, you can find that the partitions and file systems within the ECS instance are not resized. This step describes how to resize the partitions of the resized disk within the ECS instance.

1. Install the gdisk tool on the ECS instance.
   You must perform this step if the partitions are in the GPT format. Skip this step if the partitions are in the MBR format.

   yum install gdisk -y

2. Install the growpart tool.
   • Run the following command if the instance runs CentOS 7 or later:

     yum install -y cloud-utils-growpart

   • Run the following command if the instance runs Debian 9 or later or Ubuntu 14 or later.

     Update the software source.

     apt-get update

     Install cloud-guest-utils.

     apt-get install -y cloud-guest-utils

3. Run the following command to resize partitions:

   growpart /dev/vda 1

   In this example, the partition of the system disk is resized. Use a space to separate /dev/vda with 1. To resize other partitions, modify the command accordingly. An output similar to the following one is displayed.

   Note When you run the growpart /dev/vda 1 command, the unexpected output in sfdisk --version [sfdisk, from util-linux 2.23.2] error may be prompted. For information about how to troubleshoot this problem, see the FAQ section of this topic.

Step 5: Resize file systems

This step describes how to resize the file system of a partition within an ECS instance.

1. Resize the file systems within the ECS instance based on the file system types that you obtained.
   • To resize ext* (such as ext4) file systems, run the following commands:
     To resize the file system of the /dev/vda1 partition of the system disk, run the following command:

     resize2fs /dev/vda1    

     To resize the file system of the /dev/vdb1 partition of a data disk, run the following command:

     resize2fs /dev/vdb1          

     Note /dev/vda1 and /dev/vdb1 are partition names. Change the commands based on your partition names.
   • To resize xfs file systems, run the following command:

     xfs_growfs /media/vdc

     Note /media/vdc is the mount point of the /dev/vdc1 partition. Change the command based on the mount point of your partition.
2. Run the following command to check the resizing results:

   df -Th

   An output similar to the following one is displayed.

   
   After the disk is resized, check whether the new capacity of the disk is as expected.

   • If the file systems are resized and the business programs in the instance can run properly, the resizing operation is complete.
   • If the file systems fail to be resized, use the snapshot that you created in Step 1 to roll back the disk.

Operating systems that support online resizing

FAQ

• Problem description: When the growpart /dev/vda 1 command is being run, the unexpected output in sfdisk --version [sfdisk, from util-linux 2.23.2] error is prompted.
  Solution:

  1. Run the locale command to view the character encoding type of the ECS instance. If the character encoding type is not en_US.UTF-8, switch it to en_US.UTF-8.
     1. Run the following command to switch the character encoding type:

        LANG=en_US.UTF-8

     2. If the problem persists, run the following command to switch the character encoding type:

        export LC_ALL=en_US.UTF-8

     3. If the problem persists, run the following command to switch the character encoding type:

        localectl set-locale LANG=en_US.UTF-8

     4. If you are using a CentOS 8 image and the preceding solutions cannot solve the problem, run the following command to switch the character encoding type:

        export LANGUAGE=en_US.UTF-8

  2. If the problem persists, run the reboot command to restart the ECS instance.

  Notice

  After you resize the partition by switching the character encoding type, we recommend that you switch back to the original character encoding type.

• Problem description: When the growpart /dev/vda 1 command is being run, the -bash: growpart: command not found error is prompted.
  Solutions:

  1. Run the uname -a command to check the version of the Linux kernel. The procedure described in this topic applies to Linux kernel 3.6.0 and later.

     If the version of the Linux kernel is earlier than 3.6.0, you can extend partitions of a disk on the instance. For more information, see Procedure for instances with kernels earlier than 3.6.0 and Resize partitions and file systems of Linux data disks.

  2. Install the growpart tool.
     • Run the following command if the instance runs CentOS 7 or later:

       yum install -y cloud-utils-growpart

     • Run the following command if the instance runs Debian 9 or later or Ubuntu 14 or later:

       apt install -y cloud-guest-utils

Other scenarios for disk resizing

• If you want to create partitions on the resized data disk, see Option 2: Add and format MBR partitions or Option 4: Add and format GPT partitions.
• If no partition is created on your data disk and a file system is created on the raw device, see Option 5: Resize the file system of a raw data disk.