RuntimeClass is used for selecting the container runtime configuration to use to run a pod’s containers, see [runtime-class](https://kubernetes.io/docs/concepts/containers/runtime-class/). Currently, only `kata-containers` and `runc` this two `oci runtime` are supported.
1. Configure `isulad` in `/etc/isulad/daemon.json`:
`iSulad` supports the `overlay2` and `devicemapper` as storage drivers. The default value is `overlay2`.
In some scenarios, using block device type as storage drivers is a better choice, such as run a `kata-containers`. The procedure for configuring the `devicemapper` is as follows:
Create ThinPool:
```bash
$ sudo pvcreate /dev/sdb1 # /dev/sdb1 for example
$ sudo vgcreate isulad /dev/sdb
$ sudo echo y | lvcreate --wipesignatures y -n thinpool isulad -L 200G
$ sudo echo y | lvcreate --wipesignatures y -n thinpoolmeta isulad -L 20G