Disk categories and use scenarios - Container Service for Kubernetes

Disk categories

Disks are suitable for the following scenarios:

Applications requiring high disk I/O throughput without data sharing, such as MySQL and Redis.
High-speed log writing.
Data persistence independent of the pod lifecycle.

ACK supports elastic ephemeral disks, ESSD-series disks, and previous-generation disks such as standard SSDs, ultra disks, and basic disks. Features, performance, and price vary by category. Select a disk category based on your requirements.

Note

Standard SSDs, ultra disks, and basic disks are previous-generation cloud disks unavailable in some regions and zones. Use PL0 ESSDs or ESSD Entry disks instead of ultra disks and basic disks, and ESSD AutoPL disks instead of standard SSDs.

Features and scenarios

The following table compares disk features and scenarios. See Overview of Block Storage.

Disk category	Feature	Scenario
ESSD AutoPL disks	Decouple disk capacity from disk performance. Support performance provisioning. Support performance bursting.	All ESSD scenarios. Scale performance without expanding capacity. Burst performance during workload spikes.
Regional ESSDs	Deliver high IOPS. Provide zone-redundant storage.	All ESSD scenarios. Multi-zone disaster recovery for databases. Cross-zone container deployment. Self-managed or cloud-based SaaS services.
ESSDs	Deliver high IOPS. Provide low latency.	Latency-sensitive or I/O-intensive scenarios, such as: Large-scale online transaction processing (OLTP) databases NoSQL databases Elasticsearch distributed logs
ESSD Entry disks Note ESSD Entry disks can be attached only to instances of universal instance families and e economy instance families.	Deliver high IOPS. Provide low latency.	Development and testing System disks
Elastic ephemeral disks	Deliver high performance. Provide a high price-performance ratio.	Temporary data storage, including: Temporary intermediate computational results Cached data Transient files Temporary storage support for high-performance tasks

Disk performance

Disk performance varies by category. Key metrics include IOPS, throughput, and latency.

See Performance metrics.
Compare category-specific data in Disk performance and Elastic ephemeral disk performance.
Cloud disk performance is constrained by disk specifications and ECS instance type limits. See Storage I/O performance.

Cloud disk billing

Cloud disks used as volumes must use pay-as-you-go billing. Subscription disks cannot be mounted as volumes. Purchase storage capacity units (SCUs) to reduce costs.

See Block storage billing.
See Prices of block storage devices.

Note

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. See Billing FAQ.

Limitations

Cloud disks are non-shared storage. A cloud disk with multi-attach disabled can be mounted to only one pod at a time. For more information about multi-attach, see Using NVMe cloud disk multi-attach and Reservation.
A cloud disk can be mounted only to pods in the same zone. Cross-zone mounting is not supported.
Supported ECS instance types depend on the disk category.

When mounting a disk volume, verify that the ECS instance type supports the target disk category. See Instance family overview for matching rules.

Disk operations

Operation	Description	References
Mount disk volumes	Statically provisioned disk volumes Create a persistent volume (PV) from an existing cloud disk, bind it to a persistent volume claim (PVC), and mount the PVC to your application. Static provisioning prepares the PV before the container starts, suitable for reusing existing disks. Dynamically provisioned disk volumes Define disk configurations in a StorageClass and associate it with a PVC. The system automatically creates and binds a disk and PV based on the PVC and StorageClass configurations. No manual PV creation is required.	Use statically provisioned cloud disk volumes Use dynamic volumes with cloud disks
Expand disk volumes	Expand disk volumes when storage space becomes insufficient as data grows.	Expand disk volumes
Change the category of a cloud disk.	Change the category of a mounted disk to meet performance or storage requirements. For example, upgrade a standard SSD to an ESSD for higher IOPS.	Change the disk category
Use snapshots to back up data on disks	For a single disk ACK integrates cloud disk snapshots with cluster volumes through the VolumeSnapshot resource. Restore data from a snapshot by setting the dataSource parameter of your PVC. For multiple disks Individual VolumeSnapshots across multiple disks may not be created simultaneously, risking data inconsistency. Use group snapshots to back up multiple disks atomically.	Create a snapshot of a single disk volume Create group snapshots of multiple disk volumes
Encrypt data on disks	Disk encryption automatically encrypts data written to a disk and decrypts it on read, suitable for security and compliance requirements. No separate key management infrastructure is required.	Encryption overview Encrypt a disk volume
Use instant access (IA) snapshots to restore data	Restore data from an IA snapshot if an ESSD is accidentally deleted.	Best practices for data security of disk volumes

References

Use the CSI plugin to create, mount, and unmount volumes. See Manage CSI components.
To share storage across pods or zones, use NAS volumes.
For disk volume errors, see Disk volume FAQ.