You can resize a system disk or data disk to extend its capacity. This topic describes how to resize a disk for a Linux instance while the instance is running.

Prerequisites

The following table describes the requirements that must be met before you resize a disk online for a Linux instance.
Resource Requirement
Instance
  • The instance is I/O optimized.
  • The public image used by the instance supports online resizing of disks. For more information about images that support online resizing of disks, see Operating systems that support online resizing.
  • Disks on instances of the ecs.ebmc4.8xlarge, ecs.ebmhfg5.2xlarge, and ecs.ebmg5.24xlarge instance types cannot be resized online.
  • The instance is in the Running (Running) state.
  • The version of the Linux kernel of the instance is 3.6.0 or later. You can run the uname -a command to check the kernel version.

    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.

Note If your ECS instance does not meet the requirements on resizing disks online, you can resize its disks offline. For more information, see Resize disks offline for Linux instances.
Disk
  • The disk is in the In Use (In Use) state.
  • The disk is an enhanced SSD (ESSD), a standard SSD, or an ultra disk.
  • After you renew a subscription instance and downgrade its configurations, you cannot resize the subscription disks on the instance for the remainder of the current billing cycle.
  • When you resize a disk of a specific category, the specified new disk capacity cannot exceed the maximum single-disk capacity allowed for the disk category. For more information, see the "Elastic Block Storage (EBS) limits" section of the Limits topic.
Notice A disk in the master boot record (MBR) partition format cannot be resized to 2 TiB or greater. To resize an MBR disk to larger than 2 TiB, we recommend that you create a new disk larger than 2 TiB, partition and format the new disk to the GUID Partition Table (GPT) format, and then copy data from the original MBR disk to the new GPT disk. For more information about how to use the GPT format to partition and format disks, see Partition and format a data disk larger than 2 TiB in size.

Background information

The following table lists configurations of the instance and disks that are used in the examples of this topic.
Resource Description
Image used by the instance Alibaba Cloud Linux 2.1903 LTS 64-bit public image
System disk /dev/vda: uses the MBR partition format and ext4 file system, and is resized from 40 GiB to 60 GiB.
Data disk
  • /dev/vdb: uses the MBR partition format and ext4 file system, and is resized from 40 GiB to 60 GiB.
  • /dev/vdc: uses the GPT partition format and xfs file system, and is resized from 40 GiB to 60 GiB.

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.
Notice
  • After you resize the disk in the ECS console, you must resize the partitions and file systems of the disk within the instance before you can use the new capacity of the disk.
  • If you use Logical Volume Manager (LVM) to manage partitions of the disk, you must use LVM to resize the partitions and file systems after you resize the disk in the console. For more information, see Resize an LV.

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).View the partitions of the disks
    No. Partition Description
    /dev/vda1 A partition of the system disk. A value of Linux for System indicates that the partition is in the MBR format.
    /dev/vdb1 A partition of a data disk. A value of Linux for System indicates that the partition is in the MBR format.
    /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.

    View the file systems

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.growpart
    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.

    Check the resizing results
    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

The following Linux public images and custom images derived from these public images support online resizing:
  • Alibaba Cloud Linux: Alibaba Cloud Linux 2.1903 LTS 64-bit
  • CentOS:
    • CentOS 6: CentOS 6.8 and later
    • CentOS 7: CentOS 7.2 and later
    • CentOS 8 and later
  • Red Hat Enterprise Linux (RHEL):
    • RHEL 6: RHEL 6.9 and later
    • RHEL 7: RHEL 7.4 and later
    • RHEL 8 and later
  • Ubuntu: Ubuntu 16 and later
  • Debian: Debian 8 and later
  • SUSE: SUSE 12 SP2 and later
  • openSUSE: openSUSE 42.3 and later

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