Resize the system or data disk of a node - Container Service for Kubernetes

How it works

Expanding a node disk involves two layers of changes:

Increase the disk capacity — resize the underlying Elastic Compute Service (ECS) disk in the ECS console.
Extend the partition and file system — make the additional space visible to the operating system on the node.

After both steps complete, restart kubelet so that Kubernetes updates the ephemeral-storage capacity for the node.

The procedure differs slightly between system disks and data disks:

Disk type	Partition extension needed?	File system extension needed?
System disk (for example, `/dev/vda3`)	Yes — run `growpart` first	Yes — run `resize2fs`
Data disk (for example, `/dev/vdb`)	No — the disk has no extra partition	Yes — run `resize2fs` directly

Prerequisites

Before you begin, ensure that you have:

SSH access to the node. See Use Workbench to connect to a Linux instance over SSH
Read the disk resize overview to understand capacity limits and billing implications. Resizing a disk incurs charges
Confirmed which disk you are expanding: system disk or data disk

Expand the system disk

Step 1: Check the current disk state

Log on to the node and verify the current disk usage and partition layout.

Check current file system usage:
```
df -hl
```

List disk partitions:

sudo fdisk -lu

Expected output:

Disk /dev/vda: 20 GiB, 21474836480 bytes, 41943040 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: gpt
Disk identifier: FD47CD2F-8911-47B3-94A7-76CAE693CF78

Device      Start      End  Sectors  Size Type
/dev/vda1    2048     6143     4096    2M BIOS boot
/dev/vda2    6144   415743   409600  200M EFI System
/dev/vda3  415744 41940991 41525248 19.8G Linux filesystem

The Linux filesystem partition (/dev/vda3) is the one you will extend.

Troubleshooting: If /dev/vda is not listed in the output, verify that the disk is attached to the node in the ECS console.

Step 2: Increase the disk capacity in ECS

Log on to the ECS console and resize the system disk. See Resize a disk to extend the disk capacity for usage notes and step-by-step instructions.

Use online resizing so the change takes effect without rebooting the node.

Step 3: Extend the partition and file system

After the ECS disk resize completes, run the following commands on the node.

Extend the partition (/dev/vda, partition 3):
```
sudo LC_ALL=en_US.UTF-8 growpart /dev/vda 3
```
Troubleshooting: If growpart reports that the partition is already at maximum size, the ECS disk resize may not have propagated yet. Wait a few minutes and retry. If the problem persists, verify the new disk size in the ECS console.
Extend the file system:
```
sudo resize2fs /dev/vda3
```
Troubleshooting: If resize2fs returns a "bad magic number" or "No such file or directory" error, confirm that the partition device (/dev/vda3) matches the output from Step 1.

Verify the new capacity:

df -hl

Expected output (the /dev/vda3 line should reflect the new size, close to 200 GiB in this example):

Filesystem      Size  Used Avail Use% Mounted on
devtmpfs        3.7G     0  3.7G   0% /dev
tmpfs           3.7G     0  3.7G   0% /dev/shm
tmpfs           3.7G   20M  3.7G   1% /run
tmpfs           3.7G     0  3.7G   0% /sys/fs/cgroup
/dev/vda3       197G  4.5G  184G   3% /
...

Restart kubelet to update the node's ephemeral storage capacity:
```
systemctl restart kubelet
```
Important
Restarting kubelet may briefly affect workloads on the node. Schedule this step during off-peak hours.
Confirm that Kubernetes reflects the new ephemeral storage size. Replace cn-qingdao.192.XX.XX.88 with your actual node name:
```
kubectl get node cn-qingdao.192.XX.XX.88 -o yaml | grep ephemeral-storage
```
The ephemeral-storage value should be close to 200 GiB.

Expand a data disk

Step 1: Check the current disk state

Log on to the node and verify the current partition layout.

List disk partitions:

sudo fdisk -lu

Expected output:

Disk /dev/vda: 20 GiB, 21474836480 bytes, 41943040 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: gpt
Disk identifier: FD47CD2F-8911-47B3-94A7-76CAE693CF78

Device      Start      End  Sectors  Size Type
/dev/vda1    2048     6143     4096    2M BIOS boot
/dev/vda2    6144   415743   409600  200M EFI System
/dev/vda3  415744 41940991 41525248 19.8G Linux filesystem


Disk /dev/vdb: 45 GiB, 48318382080 bytes, 94371840 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes

The data disk (/dev/vdb) has no sub-partitions. Extend the file system directly on the disk device—no growpart step needed.

Troubleshooting: If /dev/vdb is not listed, verify that the data disk is attached to the node in the ECS console.

Step 2: Increase the disk capacity in ECS

Log on to the ECS console and resize the data disk to the target size (for example, 50 GiB). See Resize a disk to extend the disk capacity for step-by-step instructions.

Use online resizing so the change takes effect without rebooting the node.

Step 3: Extend the file system

After the ECS disk resize completes, run the following commands on the node.

Extend the file system directly on the data disk device:
```
sudo resize2fs /dev/vdb
```
Troubleshooting: If resize2fs returns an error about the file system type, confirm that the data disk uses ext4. If it uses a different file system type, use the corresponding resize tool for that file system.
Restart kubelet to update the node's ephemeral storage capacity:
```
systemctl restart kubelet
```
Important
Restarting kubelet may briefly affect workloads on the node. Schedule this step during off-peak hours.

Verify the new capacity:

df -hl

Expected output (the /dev/vdb line should reflect the new size, close to 50 GiB in this example):

Filesystem     Type      Size  Used Avail Use% Mounted on
devtmpfs       devtmpfs  3.7G     0  3.7G   0% /dev
tmpfs          tmpfs     3.7G     0  3.7G   0% /dev/shm
tmpfs          tmpfs     3.7G   20M  3.7G   1% /run
tmpfs          tmpfs     3.7G     0  3.7G   0% /sys/fs/cgroup
/dev/vda3      ext4      197G  4.5G  184G   3% /
/dev/vda2      vfat      200M  5.8M  195M   3% /boot/efi
/dev/vdb       ext4       49G  2.7G   44G   6% /var/lib/container
...

The /dev/vdb partition now shows close to 50 GiB, confirming the data disk was successfully expanded.

What's next

Extend the partitions and file systems of disks on a Linux instance — detailed guidance on partition and file system extension, including advanced scenarios