Resize disks online for Linux instances

Step 1: Create a snapshot

Create a snapshot for a disk to back up the data stored in the disk 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 Create Snapshot dialog box, enter a snapshot name, select tags, and then click Create .
8. Click the Snapshot tab to view the snapshot.
   When 100% appears in the Progress column that corresponds 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 be greater 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 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. Log on to the 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 the /dev/vda1 partition of the system disk and the /dev/vdb1 and /dev/vdc1 partitions of data disks.

   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 capacity of the system disk (/dev/vda) in the command output is still 40 GiB ( Disk /dev/vda: 42.9 GB ), the resizing operation fails. We recommend that you restart the instance in the ECS console.
3. Run the following command to check the file system types of existing partitions:

   
          df -Th
         

   A command output similar to the following one is displayed. In the command output, the Mounted on column lists the mount points that correspond to the file systems.

   

Step 4: Resize partitions

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

1. Install the gdisk tool on the 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 commands if the instance runs Debian 9 or later, or Ubuntu 14 or later.

     Update the software repository.

     
              apt-get update
             

     Install cloud-guest-utils.

     
              apt-get install -y cloud-guest-utils
             

3. Run the following command to resize the partition:

   
          growpart /dev/vda 1
         

   In this example, the /dev/vda1 partition of the system disk is resized. Use a space to separate /dev/vda from 1 . To resize other partitions, modify the command based on your needs. A command 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 message may appear. 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 systems of partitions within the instance.

1. Resize the file systems within the instance based on the file system types that you obtained.
   • To resize Ext* (such as Ext4) file systems, run the following commands.
     Resize the file system of the /dev/vda1 partition of the system disk.

     
               resize2fs /dev/vda1 
              

     Resize the file system of the /dev/vdb1 partition of the data disk.

     
               resize2fs /dev/vdb1 
              

     Note /dev/vda1 and /dev/vdb1 are partition names. Replace them with your actual partition names.
   • To resize a XFS file system, run the following command:

     
              xfs_growfs /media/vdc
             

     Note /media/vdc is the mount point of the /dev/vdc1 partition. Replace it with the actual mount point of your partition.
2. Run the following command to check the resize results:

   
          df -Th
         

   A command output similar to the following one is displayed.

   
   After you resize the file systems, check whether their actual sizes are consistent with the new specified values.

   • If the file system sizes are increased to the new specified values and business programs on the instance can run normally, the resizing operation is complete.
   • If the file system sizes are not increased to the new specified values, use the snapshot that you created in Step 1 to roll back the disk.

Operating systems (images) that support online resizing of disks

FAQ

• Question: When the growpart /dev/vda 1 command is run on the Linux instance, the unexpected output in sfdisk --version [sfdisk, from util-linux 2.23.2] error message appears. What do I do?
  Answer:

  1. Run the locale command to view the character encoding type of the 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 still persists, run the following command to switch the character encoding type:

        
                   localectl set-locale LANG=en_US.UTF-8
                  

     4. If 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 remains unsolved, run the reboot command to restart the instance.

  Notice

  If the partition is resized after you switch the character encoding type, we recommend that you switch back to the original character encoding type.

• Question: When the growpart /dev/vda 1 command is run on the Linux instance, the -bash: growpart: command not found error message appears. What do I do?
  Answer:

  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, resize partitions of disks after you resize the disks. 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
                 

• Question: The growpart tool used to resize partitions cannot be installed on CentOS 6.5. Why?
  Answer: The Linux kernel version of CentOS 6 is earlier than 3.6.0. To install the growpart tool on CentOS 6, perform the following steps:

  1. Change the source address of the YUM repository on CentOS 6. For more information, see Change the CentOS 6 source address.
     Note CentOS 6 has reached its end of life (EOL). To install the software package on CentOS 6 by using YUM, change the source address of the YUM repository.
  2. Install the dracut-modules-growroot tool on instances that run CentOS 6 to resize the partitions of disks. For more information, see Procedure for instances with kernels earlier than 3.6.0.

Other scenarios for disk resizing

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