云服务器 ecs怎么改系统盘

import json
import time
from tencentcloud.common import credential
from tencentcloud.common.profile.client_profile import ClientProfile
from tencentcloud.common.profile.http_profile import HttpProfile
from tencentcloud.common.exception.tencent_cloud_sdk_exception import TencentCloudSdkException
from tencentcloud.ecs.v20170312 import ecs_client, models

try:
    cred = credential.Credential("SecretId", "SecretKey")
    httpProfile = HttpProfile()
    httpProfile.endpoint = "ecs.tencentcloudapi.com"

    clientProfile = ClientProfile()
    clientProfile.httpProfile = httpProfile
    client = ecs_client.EcsClient(cred, "ap-guangzhou", clientProfile)

    req = models.ReplaceSystemDiskRequest()
    params = {
        "InstanceId": "ins-xxxxxxxx",
        "SystemDisk": {
            "DiskType": "CLOUD_PREMIUM",
            "DiskSize": 50
        }
    }
    req.from_json_string(json.dumps(params))

    resp = client.ReplaceSystemDisk(req)
    print(resp.to_json_string())

except TencentCloudSdkException as err:
    print(err)