You can extend the capacity of your system disks and data disks online to satisfy your growing business needs and increased application requirements. The changes take effect immediately after you complete the operation. You do not have to restart the ECS instance, create a new disk, or migrate data.


Before you extend a disk, make sure that your resources meet the following requirements:
  • The disk to be extended is in the In Use state, and the instance to which the disk is attached is in the Running state.
  • Check whether the instance to which the disk is attached meets the following conditions: If no, see Resize cloud disks offline.
    • The instance is I/O optimized.
    • The instance does not run on Windows Server 2003.
    • If a Windows instance is created before March 30, 2019, the version of the Red Hat VirtIO SICI driver must be later than 58011. For information about how to check the driver version, see Update the Red Hat VirtIO SCSI driver of Windows ECS instances.
    • If you are using a Linux instance, first run uname -a to check whether the kernel version is 3.6.0 or later.

Background information

Online disk extension allows you to extend a disk without restarting the ECS instance to which the disk is attached. When you extend a disk, only the storage capacity is extended. The file systems are not extended. You must manually allocate storage space for the file systems after the disk is extended. For more information, see the What to do next section in this topic.

  • To prevent data loss, create snapshots to back up your data. For more information, see Create a snapshot.
  • If a data disk adopts the MBR partition format, you cannot resize the data disk to more than 2 TiB. If you want to resize a data disk to 2 TiB while the MBR partition format is used, we recommend that you create and attach another data disk. Format a GPT partition and copy the data in the MBR partition to the GPT partition.
The following limits apply when you extend disks online:
  • For more information about limits of extending system disks and data disks, see Overview.
  • You cannot extend a disk for which a snapshot is being created.
  • You can extend ultra disks, standard SSDs, and enhanced SSDs online.
  • After you renew and downgrade a subscription instance, you cannot extend the subscription disks associated with the instance during the remaining time of the current billing cycle.
  • You cannot shrink an extended disk by any means, such as by rolling it back.
  • For Windows instances, you can only extend NTFS file systems.
  • For Linux instances, only system disks of public images listed in the following table can be extended online.
    Distribution Public image version
    CentOS 7 CentOS 7.2 and later
    CentOS 6 CentOS 6.8 and later
    Ubuntu 16 All Ubuntu 16 versions
    Ubuntu 18 All Ubuntu 18 versions
    Debian 8 Debian 8.9 and later
    Debian 9 All Debian 9 versions
    Red Hat Enterprise Linux 7 Red Hat Enterprise Linux 7.4 and later (with SAP)
    Red Hat Enterprise Linux 6 Red Hat Enterprise Linux 6.9 and later
    Red Hat Enterprise Linux 8 All Red Hat Enterprise Linux 8 versions
    SUSE 12 SUSE 12 SP2 and later (with SAP)
    openSUSE openSUSE 42.3 and later


  1. Log on to the ECS console.
  2. In the left-side navigation pane, choose Storage & Snapshots > Disks.
  3. In the top navigation bar, select a region.
  4. Find the disk to be extended and choose More > Resize Disk in the Actions column.
    Extend a disk online
  5. Select Resize Online in the Resizing Method column.
  6. Specify the capacity after resizing.
  7. Confirm the fees, read and select ECS Service Terms, and then click Resize.
  8. Complete the payment.
    Note If you do not select Resize Online or the ECS instance does not meet the requirements to be resized online, log on to the console or call the RebootInstance operation to restart the instance for the modification to take effect. For more information, see Restart an instance and RebootInstance.

What to do next

After you extend a disk, you can perform the operations listed in the following table.
Disk status What to do next
Not attached and partitioned
If the disk is a data disk in the Available state, the extended capacity takes effect immediately after you complete the payment. The following procedure describes how to extend a disk:
  1. Log on to the ECS console or call the AttachDisk operation to attach the disk. For more information, see Attach a disk.
  2. Partition and extend or format the disk:
Attached but not partitioned Partition and format the disk:
Attached and partitioned
Partition and extend the disk and format the file system: