EVS Volume Overview

For persistent storage, CCE Autopilot allows you to mount the storage volumes (PVs) created from Elastic Volume Service (EVS) disks to a path of a container. When the container is migrated within an AZ, the mounted volumes are also migrated. By using EVS volumes, you can mount the remote file directory of a storage system to a container so that data in the data volume is permanently preserved. Even if the container is deleted, the data in the data volume is still stored in the storage system.

Not all regions support EVS volumes. View the regions where EVS volumes are supported on the console. You can also view Function Overview to learn about all regions where EVS volumes are supported.

EVS Disk Specifications

EVS performance metrics include:

IOPS: the number of input/output operations performed by an EVS disk per second
Throughput: the amount of data read from and written into an EVS disk per second
I/O latency: the minimum interval between two consecutive I/O operations on an EVS disk

**Table 1** EVS disk specifications
Item	Extreme SSD	General Purpose SSD	Ultra-high I/O	High I/O
Max. capacity (GiB)	System disk: 1,024 Data disk: 32,768	System disk: 1,024 Data disk: 32,768	System disk: 1,024 Data disk: 32,768	System disk: 1,024 Data disk: 32,768
Max. IOPS	128000	20000	50000	5000
Max. throughput (MiB/s)	1000	250	350	150
Burst IOPS limit	64000	8000	16000	5000
Disk IOPS	Min. (128,000, 1,800 + 50 x Capacity)	Min. (20,000, 1,800 + 12 x Capacity)	Min. (50,000, 1,800 + 50 x Capacity)	Min. (5,000, 1,800 + 8 x Capacity)
Disk throughput (MiB/s)	Min. (1,000, 120 + 0.5 x Capacity)	Min. (250, 100 + 0.5 x Capacity)	Min. (350, 120 + 0.5 x Capacity)	Min. (150, 100 + 0.15 x Capacity)
Single-queue access latency (ms)	Sub-millisecond	1	1	1~ 3
API name	ESSD	GPSSD	SSD	SAS

For details about EVS disks, see Disk Types and Performance.

Scenario

EVS volumes can be mounted in the following modes based on application scenarios:

Using an existing EVS disk through a static PV: Use an existing EVS disk to create a PV and then mount storage to the workload through a PVC. This mode applies to scenarios where the underlying storage is available or billed on a yearly/monthly basis.
Using an EVS disk through a dynamic PV: You do not need to create EVS volumes beforehand. Instead, specify a StorageClass when creating a PVC. Then, an EVS volume and PV will be created automatically. This mode applies to scenarios where no underlying storage is available.
Dynamically mounting an EVS volume to a StatefulSet: Each pod is associated with a unique PVC and PV. After a pod is rescheduled, the original PV can still be mounted to it based on the PVC name. This mode applies to StatefulSets with multiple pods.