MAAS 区域控制器与机架控制器连接良好，但自此从未同步。 
检查机架控制器中的错误日志显示以下内容：
May 19 03:26:45 rackA maas.networks.monitor: [info] Networks monitoring service: Process ID 6121 assumed responsibility.
May 19 03:27:00 rackA maas.dhcp.probe: [error] Can't initiate DHCP probe; no RPC connection to region.
May 19 03:27:00 rackA maas.boot_image_download_service: [error] Can't initiate image download, no RPC connection to region.
May 19 03:27:16 rackA maas.service_monitor_service: [error] Can't update service statuses, no RPC connection to region.
May 19 03:28:15 rackA maas.service_monitor_service: [error] Can't update service statuses, no RPC connection to region.
May 19 03:29:15 rackA maas.service_monitor_service: [error] Can't update service statuses, no RPC connection to region.
May 19 03:30:15 rackA maas.service_monitor_service: [error] Can't update service statuses, no RPC connection to region.
May 19 03:54:42 rackA maas.networks.monitor: [info] Networks monitoring service: Process ID 9896 assumed responsibility.
May 19 03:54:43 rackA maas.tftp: [warn] No boot images have been imported from the region.
May 19 03:54:47 rackA maas.import-images: [info] Started importing boot images.
May 19 03:54:47 rackA maas.import-images: [info] Downloading image descriptions from http://192.168.1.52/MAAS/images-stream/streams/v1/index.json
May 19 03:54:48 rackA maas.import-images: [info] Downloading boot resources from http://192.168.1.52/MAAS/images-stream/streams/v1/index.json
May 19 03:57:59 rackA maas.networks.monitor: [info] Networks monitoring service: Process ID 10278 assumed responsibility.
May 19 03:58:02 rackA maas.tftp: [warn] No boot images have been imported from the region.
May 19 03:58:04 rackA maas.import-images: [info] Started importing boot images.
May 19 03:58:04 rackA maas.import-images: [info] Downloading image descriptions from http://192.168.1.52:5240/MAAS/images-stream/streams/v1/index.json
May 19 03:58:05 rackA maas.import-images: [info] Downloading boot resources from http://192.168.1.52:5240/MAAS/images-stream/streams/v1/index.json
May 19 03:58:30 rackA maas.refresh: [info] Refreshing rack controller hardware information.
May 19 03:58:31 rackA maas.service_monitor: [info] Service 'ntp' has been restarted. Its current state is 'on' and 'running'.
May 19 04:05:29 rackA maas.import-images: [info] Updating boot image iSCSI targets.
May 19 04:05:29 rackA maas.import-images: [warn] Unable to import boot images; cleaning up failed snapshot and cache.
May 19 04:05:30 rackA maas.boot_image_download_service: [error] Failed to download images: Invalid sha256 Checksum at http://192.168.1.52:5240/MAAS/images-stream/ubuntu/amd64/hwe-x-lowlatency/trusty/20170509/boot-kernel. Found 3004a1440bcbe73107d38b7ffdb6c8d856cdae25e4fde11a908d438e6baaedcc. Expected 638678c39b65bb2e8791298bd2e2e73317b19208663b7af72c08a4f088d70f23. read 5857280 bytes expected 5850224 bytes. (size 5857280 expected 5850224)
May 19 04:07:27 rackA maas.service_monitor: [error] While monitoring service 'ntp_rack' an error was encountered: Connection to the other side was lost in a non-clean fashion.
May 19 04:07:27 rackA maas.power_monitor_service: [error] Failed to query nodes' power status: Connection to the other side was lost in a non-clean fashion.
May 19 04:07:59 rackA maas.import-images: [info] Started importing boot images.
May 19 04:07:59 rackA maas.import-images: [info] Downloading image descriptions from http://192.168.1.52:5240/MAAS/images-stream/streams/v1/index.json
May 19 04:08:00 rackA maas.import-images: [info] Downloading boot resources from http://192.168.1.52:5240/MAAS/images-stream/streams/v1/index.json
May 19 04:10:57 rackA maas.networks.monitor: [info] Networks monitoring service: Process ID 1164 assumed responsibility.
May 19 04:11:12 rackA maas.dhcp.probe: [error] Can't initiate DHCP probe; no RPC connection to region.
May 19 04:11:12 rackA maas.boot_image_download_service: [error] Can't initiate image download, no RPC connection to region.
May 19 04:11:27 rackA maas.service_monitor_service: [error] Can't update service statuses, no RPC connection to region.
May 19 04:12:27 rackA maas.service_monitor_service: [error] Can't update service statuses, no RPC connection to region.
May 19 04:13:27 rackA maas.service_monitor_service: [error] Can't update service statuses, no RPC connection to region.
May 19 04:14:27 rackA maas.service_monitor_service: [error] Can't update service statuses, no RPC connection to region.
May 19 04:15:27 rackA maas.service_monitor_service: [error] Can't update service statuses, no RPC connection to region.
May 19 04:16:04 rackA maas.networks.monitor: [info] Networks monitoring service: Process ID 1435 assumed responsibility.
May 19 04:16:09 rackA maas.import-images: [info] Started importing boot images.
May 19 04:16:09 rackA maas.import-images: [info] Downloading image descriptions from http://192.168.1.52:5240/MAAS/images-stream/streams/v1/index.json
May 19 04:16:10 rackA maas.import-images: [info] Downloading boot resources from http://192.168.1.52:5240/MAAS/images-stream/streams/v1/index.json
May 19 04:16:11 rackA maas.tftp: [warn] No boot images have been imported from the region.
May 19 04:16:34 rackA maas.refresh: [info] Refreshing rack controller hardware information.
May 19 04:16:36 rackA maas.service_monitor: [info] Service 'ntp' has been restarted. Its current state is 'on' and 'running'.
May 19 04:23:57 rackA maas.power_monitor_service: [error] Failed to query nodes' power status: Connection to the other side was lost in a non-clean fashion.
May 19 04:23:59 rackA maas.service_monitor: [error] While monitoring service 'ntp_rack' an error was encountered: Connection to the other side was lost in a non-clean fashion.
May 19 04:24:04 rackA maas.power_monitor_service: [error] Lost connection to region controller.
May 19 05:10:16 rackA maas.drivers.power.manual: [info] You need to check power state of 8dhscs manually.
May 19 05:10:16 rackA maas.drivers.power.manual: [info] You need to check power state of 8dhscs manually.
May 19 05:40:16 rackA maas.drivers.power.manual: [info] You need to check power state of 8dhscs manually.
May 19 05:45:22 rackA maas.service_monitor: [info] Service 'maas-dhcpd' has been restarted. Its current state is 'on' and 'running'.
May 19 05:45:23 rackA maas.service_monitor: [info] Service 'maas-dhcpd6' has been restarted. Its current state is 'on' and 'running'.
May 19 05:45:37 rackA maas.service_monitor: [info] Service 'maas-dhcpd' has been restarted. Its current state is 'on' and 'running'.
May 19 05:46:16 rackA maas.service_monitor: [info] Service 'maas-dhcpd' has been restarted. Its current state is 'on' and 'running'.
May 19 05:46:31 rackA maas.service_monitor: [info] Service 'maas-dhcpd' is not off, it will be stopped.
May 19 05:46:31 rackA maas.service_monitor: [info] Service 'maas-dhcpd' has been stopped and is 'dead'.
May 19 05:46:31 rackA maas.service_monitor: [info] Service 'maas-dhcpd6' is not off, it will be stopped.
May 19 05:46:31 rackA maas.service_monitor: [info] Service 'maas-dhcpd6' has been stopped and is 'dead'.
May 19 06:00:04 rackA maas.power_monitor_service: [error] Lost connection to region controller.
May 19 06:41:34 rackA maas.power_monitor_service: [error] Lost connection to region controller.
May 19 06:41:34 rackA maas.service_monitor: [error] While monitoring service 'ntp_rack' an error was encountered: Connection was closed cleanly.
这是问题的另一张图片，几个小时以来一直在加载。
无法弄清楚问题出在哪里。
答案1
我的解决方案是，我只是使用以下命令重新注册了该设备：
sudo maas-rack register --url http://192.168.1.11:5240/MAAS --secret $secret
如果你不知道在哪里获取 MAAS 密钥，请按照以下步骤操作：
- 转到您的 MAAS WebUI，
- 选择
Nodes->Controllers->Add Rack Controller:
将会下拉一个类似这样的黑框：
- 复制和粘贴命令（或在终端上拖放）。
这已修复该问题。