Disks are non-shared, low-latency, and high-reliability block-level random storage. Disks are suitable for applications that require high IOPS and low latency but do not require data sharing, such as databases. Container Service for Kubernetes (ACK) allows you to mount Enterprise SSDs (ESSDs) and ESSD AutoPL disks to pods as volumes to meet the requirements for data persistence.
Disk categories
Disks are suitable for the following scenarios:
You want to create applications that require high disk I/O throughput and do not require data sharing. The applications can use storage services such as MySQL and Redis.
You want to write logs at high speeds.
You want to persist data in a way that is independent of the pod lifecycle.
ACK supports ESSDs, ESSD AutoPL disks, ESSD Entry disks, and disks of the previous generation, such as standard SSDs, ultra disks, and basic disks. The features, performance, and price of a disk varies based on its category. When you mount a disk volume, we recommend that you select a suitable disk category based on your business requirements and scenarios.
Standard SSDs, ultra disks, and basic disks are cloud disks of the previous generation and are unavailable for purchase in specific regions and zones. We recommend that you use ESSDs at performance level 0 (PL0 ESSDs) or ESSD Entry disks instead of ultra disks and basic disks and use ESSD AutoPL disks instead of standard SSDs.
Features and scenarios of disk categories
The following table describes the features and scenarios of different disk categories. For more information, see Overview of Block Storage.
Disk category | Feature | Scenario |
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| Latency-sensitive applications or I/O-intensive business scenarios, such as:
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ESSD Entry disks Note ESSD Entry disks can be attached to only instances of universal instance families and e economy instance families. |
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Disk performance
The performance of a disk varies based on its category. The performance metrics of disks include IOPS, throughput, and latency.
For more information about the performance metrics of disks, see Performance metrics.
For more information about the performance data of different disk categories, see Performance of cloud disks.
The final performance of cloud disks is subject to the disk specification limits and Elastic Compute Service (ECS) instance type limits. For more information, see Storage I/O performance.
Billing of cloud disks
Cloud disks support the pay-as-you-go and subscription billing methods. However, only pay-as-you-go disks can be mounted. You can purchase storage capacity units (SCUs) to reduce the disk cost.
For more information about the billing rules of cloud disks, see Block storage devices.
For more information about the prices of disks, see Prices of block storage devices.
When you change the billing method of an ECS instance from pay-as-you-go to subscription, do not select Switch to Subscription. Otherwise, workloads on the instance cannot be restarted. As a result, workloads on the instance may be affected. For more information, see Why do applications fail to restart after I change the billing method of a data disk mounted to an ECS instance from pay-as-you-go to subscription when I change the billing method of the ECS instance from pay-as-you-go to subscription?
Limits
Disks cannot be shared. If multi-attach is not enabled for disks, each disk can be mounted to only one pod. For information about the multi-attach feature, see Use the multi-attach and NVMe reservation features of NVMe disks.
You can mount a disk only to a pod that resides in the same zone as the disk.
The ECS instance types to which a cloud disk can be attached depend on the category of the disk.
When you mount a disk volume to a pod, make sure that the instance type of the ECS instance on which the pod runs supports the category of the disk that you want to mount. For more information about the matching rules between disk categories and ECS instance types, see Overview of instance families.
Disk operations
Operation | Description | References |
Mount disk volumes |
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Expand disk volumes | As your business and application data grow, the storage space of your disk volumes may become insufficient. In this case, you can expand your disk volumes to meet the increasing storage requirements. | |
Change the category of a cloud disk. | If the disk volume you use does not meet your requirements for performance and storage, you can change the category of the mounted disk. Assume that you have mounted a standard SSD for your application. If your application requires a higher IOPS, you can change the category of the disk from standard SSD to ESSD. | |
Use snapshots to back up data on disks |
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Encrypt data on disks | After you enable the disk encryption feature, the system automatically encrypts data transmitted to a disk and decrypts the data when it is read. Disk encryption is suitable for scenarios that require high security or have compliance requirements. You can protect the privacy and autonomy of your data without the need to create and maintain a key management infrastructure. | |
Use instant access (IA) snapshots to restore data | If data loss occurs due to an accidental ESSD deletion, you can use the IA snapshot of the ESSD to restore the data in the ESSD. |
References
You can use the Container Storage Interface (CSI) plug-in to create, mount, and unmount volumes. For more information, see Manage the CSI plug-in
If you want to share storage across pods or zones, we recommend that you use File Storage NAS (NAS) volumes.
If errors occur when you use disk volumes, refer to FAQ about disk volumes.