Container Service for Kubernetes:Disk volume overview

Disk Category

Feature

Usage scenario

Billing

ESSD AutoPL disks

• Decouple disk capacity from disk performance.

• Support the performance provision feature.

• Support the performance burst feature.

• All scenarios for which ESSDs are suitable.

• Scenarios in which disk performance needs to be increased without the need for disk capacity extension.

• Scenarios in which business workloads significantly fluctuate and disks need to burst their performance when workload spikes occur.

• You are charged for disk capacity.

• You are charged for the provisioned performance on a pay-as-you-go basis after the performance provision feature is enabled.

• You are charged for the burst performance on a pay-as-you-go basis after the performance burst feature is enabled.

ESSDs

• Deliver high IOPS.

• Deliver low latency.

Latency-sensitive applications or I/O-intensive business scenarios, such as:

• Large-scale online transaction processing (OLTP) databases

• NoSQL databases

• Elasticsearch distributed logs

You are charged for disk capacity.

ESSD Entry disks

• Deliver high IOPS.

• Deliver low latency.

• Development and testing business

• Usage as system disks.

You are charged for disk capacity.

Cloud disk category

Feature

Usage scenario

Billing

Standard SSDs

• Deliver high random read/write performance.

• Provide high reliability.

• I/O-intensive applications

• Small and medium-sized relational databases and NoSQL databases

You are charged for disk capacity.

Ultra disks

• Deliver high cost efficiency.

• Provide high reliability.

• Development and testing business

• Usage as system disks.

You are charged for disk capacity.

Basic disks

Deliver high cost efficiency.

Low-cost development and testing business that does not require high storage performance

You are charged for disk capacity.

Item

Description

Disk category

You cannot mount or unmount subscription disks. Use pay-as-you-go disks or use disks together with storage capacity units (SCUs).

Whether it can be shared

Alibaba Cloud disks cannot be shared. Each disk can be mounted to only one pod.

Relationship with ECS instances

• A disk can be mounted only to an ECS instance that resides in the same zone as the disk. Cross-zone mounting is not supported.

• Before you can mount a disk, make sure that the disk type matches the ECS instance type used in your cluster. Ultra disks cannot be used in ECS instances of the seventh generation or later. For more information about disk types supported by each ECS instance type, see Overview of instance families.

Number of mounted disks and disk capacity

• The maximum number of disks that can be mounted to a node depends on the instance type of the node. For more information, see Overview of instance families.

• The minimum capacity of a single PL0 Enterprise SSD (ESSD) or ESSD AutoPL disk is 1 GiB and the maximum capacity is 32 TiB, which equals to 32,768 GiB.

Application type

Mount a disk to a StatefulSet.

Configure Application Parameters

If you configure the securityContext.fsgroup parameter in the application template, the kubelet performs the chmod and chown operations after a disk volume is mounted, which may increase the mounting time. For more information about how to reduce the mounting time, see Cause 3 in the Why does the system prompt Unable to attach or mount volumes: unmounted volumes=[xxx], unattached volumes=[xxx]: timed out waiting for the condition when I start a pod that uses a disk volume? section.

Performance indicator

ESSD AutoPL disk

ESSD

ESSD Entry disk

Standard SSD

Ultra disk

Basic disk

Performance Level

An ESSD AutoPL disk can decouple capacity from performance and deliver baseline performance that is equal to the baseline performance of an ESSD PL1 disk. You can configure provisioned performance and burst performance for ESSD AutoPL disks.

PL3

PL2

PL1

PL0

None

None

None

None

Single-disk capacity range (GiB)

1~65,536

1,261~65,536

461~65,536

20~65,536

1~65,536

10~32,768

20~32,768

20~32,768

5~2,000

Max IOPS/Min IOPS

1,000,000/3,000

1,000,000/64,850

100,000/24,872

50,000/2,800

10,000/1,812

6,000/1,880

25,000/2,400 ^②

5,000/1,960

Hundreds

Max throughput/Min throughput (MB/s)

4,096/125

4,000/750.5

750/350.5

350/130

180/100

150/101.5

300/130 ^②

140/103

30~40

Formula for calculating single-disk IOPS^①

Baseline performance:

max{min{1,800 + 50 × Capacity, 50,000}, 3,000}

Provisioned performance: min{Provisioned IOPS, 50,000}

Burst performance: min{IOPS supported by the instance type, 1,000,000}

min{1,800 + 50 × Capacity, 1,000,000}

min{1,800 + 50 × Capacity, 100,000}

min{1800 + 50 × Capacity, 50,000}

min{1,800+12 × Capacity, 10,000}

min{1,800 + 8 × Capacity, 6,000}

min{1,800 + 30 × Capacity, 25,000}

min{1,800 + 8 × Capacity, 5,000}

None

Formula for calculating single-disk throughput (MB/s) ^①

Baseline performance:

max{min{120 + 0.5 × Capacity, 350}, 125}

Provisioned performance: min{16 KB × Provisioned IOPS/1,024, Maximum throughput per disk}

Burst performance: min{Throughout supported by the instance type, 4 GB/s}

min{120 + 0.5 × Capacity, 4,000}

min{120 + 0.5 × Capacity, 750}

min{120 + 0.5 × Capacity, 350}

min{100 + 0.25 × Capacity, 180}

min{100 + 0.15 × Capacity, 150}

min{120 + 0.5 × Capacity, 300}

min{100 + 0.15 × Capacity, 140}

None

Data reliability

99.9999999%

99.9999999%

99.9999999%

99.9999999%

99.9999999%

99.9999999%

99.9999999%

99.9999999%

99.9999999%

Average one-way random write latency in milliseconds (block size = 4 KB)

0.2

0.2

0.2

0.2

0.3~0.5

1~3

0.5~2

1~3

5~10

API parameter value

cloud_auto

cloud_essd

cloud_essd

cloud_essd

cloud_essd

cloud_essd_entry

cloud_ssd

cloud_efficiency

cloud

Business requirement

Description

References

Store application data

• Statically provisioned disk volumes: If the disk that you created meets the limits, you can use the disk to create a PV and mount the PV to the workload by using the PVC. Statically provisioned disk volumes cannot be expanded.

• Dynamically provisioned disk volumes: You do not need to create disks in advance. You can specify a StorageClass when you create a PVC. Then, the system automatically purchases a disk and provisions a PV. Dynamically provisioned disk volumes can be expanded.

• Use a statically provisioned disk volume

• Use a dynamically provisioned disk volume

Insufficient disk capacity

If you use a dynamically provisioned disk volume and the disk space is insufficient, you can use one of the following methods to expand the disk: For more information, see Overview.

• Expansion without service interruptions: You can expand a disk volume and its file system without service interruptions.

• Manual expansion: You can manually expand a disk volume and run the resize2fs command to manually expand the file system.

• Automatic expansion: You can configure one or more expansion policies to automatically expand a disk volume when the usage of the disk volume exceeds the specified threshold.

• Expand a disk volume without service interruptions

• Manually expand a disk volume

• Automatically expand a disk volume (public preview)

Change the type of a cloud disk

If your business scenario requires disk expansion and your application requires a higher IOPS, you can upgrade the disk. For example, you can upgrade the disk from standard SSD to ESSD.

Change the type of a cloud disk

Back up disk data

Integrate the disk backup (volume snapshots) and restoration mechanism with Container Service for Kubernetes (ACK), and create volume snapshots by using VolumeSnapshots. Restore data by setting dataSource to the related PVC.

Use volume snapshots created from disks

Encrypt disk data

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.

• Encryption overview

• Encrypt a disk volume

Ensure data security of cloud storage

If data corruption occurs when you expand an ESSD without service interruptions or data loss occurs due to an accidental ESSD deletion, you can use the instant access (IA) snapshot feature of ESSDs to restore the data in the ESSD.

Best practices for data security of disk volumes