Create a pod with a specified local disk instance type - Elastic Container Instance

This topic describes how to specify Elastic Compute Service (ECS) instance types that use a local disk to create an Elastic Container Instance (ECI) pod.

Supported instance type families

A local disk is a local hard drive on the physical machine where the instance resides. Local disks offer low latency, high random input/output operations per second (IOPS), high throughput, and excellent value. However, because a local disk is part of a single physical machine, it is susceptible to single points of failure. For more information, see Local disks.

Important

Local disks are part of a single physical machine. Therefore, data reliability depends on the reliability of the physical machine. This creates a risk of single points of failure. For more information, see Notes on local disks.

The following ECS instance families with local disks are supported:

Category	Instance family
Local SSD	i4, i4g, i3, i3g, i2, i2g
Big data	d1
Network-enhanced big data	d1ne
GPU-accelerated compute-optimized	gn5

Note

gn5 is a GPU-accelerated instance type. If you select this instance family, you must also specify GPU-related parameters in addition to local disk-related parameters.

For more information about ECS instance types, see the following topics:

Configurations

You can add the Kubernetes. aliyun.com/eci-use-specs annotation to the pod metadata to specify ECS instance types that use a local disk. When you mount your local disk, you can set the medium parameter to LocalRaid0 under EmptyDir to use the disk in a RAID 0 configuration and mount it to a specified path.

Example:

Run the following command to create a pod by specifying ECS instance types that use a local disk.

kubectl create -f localdisk-test.yaml

The following code provides an example in YAML format.

apiVersion: apps/v1
kind: Deployment
metadata:
  name: localdisk-test
  labels:
    app: test
spec:
  replicas: 1
  selector:
    matchLabels:
      app: nginx
  template:
    metadata:
      name: nginx-test
      labels:
        app: nginx
        alibabacloud.com/eci: "true" 
      annotations:
        k8s.aliyun.com/eci-use-specs: "ecs.i2g.2xlarge,ecs.i2.xlarge"  # Specify the supported ECS instance types with a local disk. You can specify up to five instance types.
    spec:
      containers:
      - name: nginx
        image: registry.cn-shanghai.aliyuncs.com/eci_open/nginx:1.14.2
        ports:
        - containerPort: 80
        volumeMounts:
          - name: localdisk
            mountPath: /localdisk-test
      volumes:                               # Mount the local disk
        - name: localdisk
          emptyDir:
            medium: LocalRaid0

View the information about the mounted local disk.

After the pod is created, view the pod information. You can see that a RAID 0 configuration (/dev/md0) is generated for the local disk, and the disk is mounted to the specified path, which is /localdisk-test in the following example.

xxx:~$ kubectl get pod
NAME                              READY   STATUS    RESTARTS   AGE
localdisk-test-5f8c979c48-j4bkj   1/1     Running   0          76s
xxx:~$ kubectl exec -it localdisk-test-5f8c979c48-j4bkj -- bash
root@localdisk-test-5f8c979c48-j4bkj:/# df -h
Filesystem      Size  Used Avail Use% Mounted on
overlay          30G  4.1G   26G  14% /
tmpfs            64M     0   64M   0% /dev
tmpfs            16G     0   16G   0% /sys/fs/cgroup
/dev/md0        879G   77M  835G   1% /localdisk-test
/dev/vda4        30G  4.1G   26G  14% /etc/hosts
overlay         8.8G  4.9G  3.5G  59% /etc/hostname
shm              64M     0   64M   0% /dev/shm
tmpfs            32G   12K   32G   1% /run/secrets/kubernetes.io/serviceaccount
tmpfs            16G     0   16G   0% /proc/acpi
tmpfs            16G     0   16G   0% /sys/firmware