VKE clusters allow you to specify the underlying attributes and features of a PV during formatting by using formatting parameters when you mount the PV in a pod. This topic describes how to specify formatting parameters when you use EBS volumes.

Background information

What are formatting parameters

Formatting parameters are specified when a file system is created (formatted) for the first time. The parameters are mainly used to specify the underlying attributes, performance, features, and adaptation logic of the file system, and replace the default format configuration. This ensures the file system is precisely adapted to business scenarios, such as small file storage, high I/O read/write operations, and large-capacity disks. It also ensures storage efficiency and data adaptability.

The following table describes common usage scenarios and descriptions of formatting parameters.

Application scenario	Scenario description
Define the basic storage unit of the file system	Configure core attributes, such as block size and inode allocation ratio, which determine how the file system stores data and manages file indexes. For example: In scenarios with multiple small files, such as logs and caches, use a smaller block size to reduce disk space waste. In scenarios with multiple large files, such as videos and databases, use a larger block size to improve read and write efficiency.
Performance and feature trade-offs	Enable or disable specific file system features or optimize key performance parameters to balance performance, security, and disk space. To achieve optimal write performance, you can disable the log feature, such as -O ^has_journal in the EXT4 system. In high I/O business scenarios, you can expand the log buffer, such as -l size=64m in the XFS system, to improve log read and write efficiency. In non-core storage scenarios, you can disable multiple metadata replicas to save disk space.
Adapt to underlying hardware and business requirements	Match the file system with the underlying disk (such as sector size) and business scenarios (such as large-capacity storage and distributed deployment) to prevent incompatibility or performance loss. Align the file system with the physical sector size of the disk to reduce extra I/O operations. In large-capacity disk scenarios, optimize the indexing strategy to prevent decreased file query efficiency.

Common formatting parameters

Supported formatting parameters vary depending on the file system type selected for EBS volumes.

When you select EXT4 as the file system type, see the official documentation for supported parameters.

When you select XFS as the file system type, see the official documentation for supported parameters.

Usage limits

To specify volume formatting parameters, the csi-ebs add-on must be upgraded to v1.3.0 or later. For details, see Upgrading add-ons.

Formatting parameters take effect only if the volume is formatted for the first time, and do not support dynamic modification.

Procedure

Configuring PVs

When you configure a PersistentVolume (PV) of the EBS type, you can specify formatting parameters by using the console or kubectl.

Configuring through the console

Configuring through kubectl

Log in to the VKE console.

In the left navigation bar, click Cluster. Click the name of the target cluster to go to the cluster management page.

In the left navigation bar on the cluster management page, click Storage > PersistentVolume.

Click Create PersistentVolume and configure parameters on the page that appears. In the Advanced settings section, click Add formatting parameter to specify the formatting parameters for the PV.

After the configuration is complete, you can create a PersistentVolumeClaim (PVC), associate it with the PV, and then mount it in the container. For details, see Using static PVs of the EBS type.

Configuring an SC

When you configure a StorageClass (SC) of the EBS type, you can specify formatting parameters by using the console or kubectl.

Configuring through the console

Configuring through kubectl

Log in to the VKE console.

In the left navigation bar, click Cluster. Click the name of the target cluster to go to the cluster management page.

In the left navigation bar on the cluster management page, click Storage > StorageClass.

Click Create StorageClass and configure parameters on the page that appears. In the Advanced settings section, click Add formatting parameter to specify the formatting parameters for the SC.

After the configuration is complete, you can create a PVC, associate it with the SC, and then mount it in the container. For details, see Using dynamic PVs of the EBS type.

Validating results

If you specify formatting parameters when you create a PV of the EBS type, you can check whether the parameters take effect after the configuration is complete. This topic uses the formatting configuration mkfsOptions: "-O bigalloc -C 16384" as an example.

Use ECS Terminal to log in to the node where the pod is located. For details, see ECS Terminal.

Run the following command to check whether the mkfsOptions formatting parameters have taken effect. /dev/vdc is the logical identifier of the volume when it is mounted on the node.

tune2fs -l /dev/vdc

The expected result is as follows.

In the Filesystem features line, the bigalloc field can be found, which indicates that the bigalloc feature of the EXT4 file system has been enabled.

In the Block size line, the value is 4096, which indicates the default block size in the EXT4 system is 4096 bytes (4 KB). In this case, the formatting parameter -C 16384 allocates a total size of 16384 * 4096 = 64 MB for the log buffer.

tune2fs 1.44.5 (15-Dec-2018)
...
Filesystem features: has_journal ext_attr resize_inode dir_index filetype needs_recovery extent 64bit flex_bg sparse_super large_file huge_file dir_nlink extra_isize bigalloc metadata_csum
...
Block size: 4096
Journal inode: 8
...

Volcengine Kubernetes Engine