Host

Overview

A host, also known as a compute node, is a physical server that provides VM instances with compute, network, and storage resources.

Hosts are core assets in ZStack. VM instances run on hosts.

As shown in Figure 1.

Inventory

Host Inventory

Name	Description	Optional	Optional Value	Starting Version
uuid	The UUID. For more information, see Resource Property.			0.6
name	The name. For more information, see Resource Property.			0.6
description	The description. For more information, see Resource Property.	Yes		0.6
zoneUuid	The zone UUID. For more information, see Zone.			0.6
clusterUuid	The parent cluster UUID. For more information, see Cluster.			0.6
managementIp	The management IP address. For more information, see Management IP.			0.6
hypervisorType	The hypervisor type. For more information, see Cluster Hypervisor Type.			0.6
state	The state. For more information, see State.		Enabled Disabled PreMaintenance Maintenance	0.6
status	The status. For more information, see Status.		Connecting Connected Disconnected	0.6
createDate	The creation date. For more information, see Resource Property.			0.6
lastOpDate	The last operation date. For more information, see Resource Property.			0.6
userTags	The user tags. For more information, see CreateUserTag.	Yes		0.6
systemTags	The system tags. For more information, see CreateSystemTag.	Yes		0.6
cpuNum	The number of vCPUs. For more information, see CPU Capacity.			0.6
cpuSockets				0.6
availableCpuCapacity				0.6
availableMemoryCapacity				0.6
totalCpuCapacity				0.6
totalMemoryCapacity				0.6

Sample

{     "inventories": {             "availableCpuCapacity": 37,             "availableMemoryCapacity": 4965064704,             "clusterUuid": "967a353c2893409dab9312cf3033a98c",             "cpuNum": 4,             "cpuSockets": 1,             "createDate": "Oct 30, 2017 3:02:06 PM",             "description": "",             "hypervisorType": "KVM",             "lastOpDate": "Oct 31, 2017 10:41:19 AM",             "managementIp": "10.0.146.122",             "name": "Host-1",             "sshPort": 22,             "state": "Enabled",             "status": "Connected",             "totalCpuCapacity": 40,             "totalMemoryCapacity": 8186290176,             "username": "root",             "uuid": "a4049fd68e1b487f8f91786d17ad37e1",             "zoneUuid": "e59b71e99d8a4ea1952b578388b8cd1d"         } }

Host Network Bonding Inventory

Name	Description	Optional	Starting Version
uuid	The UUID. For more information, see Resource Property.		3.9.0
hostUuid	The host UUID.		3.9.0
bondingName	The bond name.		3.9.0
mode	The bond mode.		3.9.0
xmitHashPolicy	The hash policy.		3.9.0
miiStatus	The MII status.		3.9.0
mac	The MAC address.		3.9.0
ipAddresses	The IP address.		3.9.0
miimon	The MII monitoring interval.		3.9.0
allSlavesActive			3.9.0
groupBy	Groups rows into subgroups based on values of columns or expressions. This parameter is equivalent to the Group By clause in MySQL, such as groupBy=type.	Yes	3.9.0
createDate	The creation date. For more information, see Resource Property.		3.9.0
lastOpDate	The last operation date. For more information, see Resource Property.		3.9.0
userTags	The user tags. For more information, see CreateUserTag.	Yes	3.9.0
systemTags	The system tags. For more information, see CreateSystemTag.	Yes	3.9.0

Sample

{   "inventories": [     {       "uuid": "2e2226e18e853f20a5791684a1b644c8",       "hostUuid": "903696c585a639bb8049713b98d93437",       "bondingName": "bond0",       "mode": "active-backup 1",       "xmitHashPolicy": "layer2 0",       "miiStatus": "up",       "mac": "ac:1f:6b:93:6c:8c",       "ipAddresses": [         "172.20.0.116/16"       ],       "miimon": 100.0,       "allSlavesActive": true,       "createDate": "Nov 14, 2017 10:20:57 PM",       "lastOpDate": "Nov 14, 2017 10:20:57 PM",       "slaves": [         {           "uuid": "17a40aa475cf322494ea82e09066892e",           "hostUuid": "903696c585a639bb8049713b98d93437",           "bondingUuid": "2e2226e18e853f20a5791684a1b644c8",           "interfaceName": "eno1",           "interfaceType": "bondingSlave",           "speed": 1000.0,           "slaveActive": true,           "carrierActive": true,           "mac": "ac:1f:6b:93:6c:8c",           "createDate": "Nov 14, 2017 10:20:57 PM",           "lastOpDate": "Nov 14, 2017 10:20:57 PM"         },         {           "uuid": "c3716c87b9173cbb8315e7d7f3645bc4",           "hostUuid": "903696c585a639bb8049713b98d93437",           "bondingUuid": "2e2226e18e853f20a5791684a1b644c8",           "interfaceName": "eno2",           "interfaceType": "bondingSlave",           "speed": 1000.0,           "slaveActive": false,           "carrierActive": false,           "mac": "ac:1f:6b:93:6c:8c",           "createDate": "Nov 14, 2017 10:20:57 PM",           "lastOpDate": "Nov 14, 2017 10:20:57 PM"         }       ]     }   ] }

Host Network Interface Inventory

Name	Description	Optional	Starting Version
uuid	The UUID. For more information, see Resource Property.		3.9.0
hostUuid	The host UUID.		3.9.0
bondingUuid	The bond UUID.		3.9.0
interfaceName	The interface name.		3.9.0
interfaceType	The interface type. Options: nomaster, bridgeSlave, and bondSlave.		3.9.0
speed	The interface speed.		3.9.0
slaveActive	The bond link status.		3.9.0
carrierActive	The physical link status.		3.9.0
ipAddresses	The IP address.		3.9.0
mac	The MAC address.		3.9.0
pciDeviceAddress	The PCI address of the interface.		3.9.0
groupBy	Groups rows into subgroups based on values of columns or expressions. This parameter is equivalent to the Group By clause in MySQL, such as groupBy=type.	Yes	3.9.0
createDate	The creation date. For more information, see Resource Property.		3.9.0
lastOpDate	The last operation date. For more information, see Resource Property.		3.9.0
userTags	The user tags. For more information, see CreateUserTag.	Yes	3.9.0
systemTags	The system tags. For more information, see CreateSystemTag.	Yes	3.9.0

Sample

{   "inventories": [     {       "uuid": "310ca8ce7010363ca7ac83d37373238f",       "hostUuid": "7f8d05522f01397e97f60d84f5ffa2b9",       "bondingUuid": "6fbe88605eed35ba95399687585be3d1",       "interfaceName": "eno1",       "interfaceType": "bondingSlave",       "speed": 1000.0,       "slaveActive": true,       "carrierActive": true,       "mac": "98:03:9b:00:ea:f1",       "createDate": "Nov 14, 2017 10:20:57 PM",       "lastOpDate": "Nov 14, 2017 10:20:57 PM"     },     {       "uuid": "3213802883d13c72b54c084233c4de2a",       "hostUuid": "7f8d05522f01397e97f60d84f5ffa2b9",       "bondingUuid": "6fbe88605eed35ba95399687585be3d1",       "interfaceName": "eno2",       "interfaceType": "bondingSlave",       "speed": 1000.0,       "slaveActive": false,       "carrierActive": false,       "mac": "98:03:9b:00:ea:f1",       "createDate": "Nov 14, 2017 10:20:57 PM",       "lastOpDate": "Nov 14, 2017 10:20:57 PM"     },     {       "uuid": "3015b6b0c74d316699ebe09dc60e1001",       "hostUuid": "7f8d05522f01397e97f60d84f5ffa2b9",       "interfaceName": "ens2f0",       "interfaceType": "noMaster",       "speed": 1000.0,       "slaveActive": true,       "carrierActive": true,       "ipAddresses": [         "169.254.0.115/24"       ],       "mac": "98:03:9b:00:ea:f2",       "createDate": "Nov 14, 2017 10:20:57 PM",       "lastOpDate": "Nov 14, 2017 10:20:57 PM"     },     {       "uuid": "e3b513e177a1313a93b32b290643f849",       "hostUuid": "7f8d05522f01397e97f60d84f5ffa2b9",       "interfaceName": "ens2f1",       "interfaceType": "bridgeSlave",       "speed": 1000.0,       "slaveActive": false,       "carrierActive": false,       "mac": "98:03:9b:00:ea:f3",       "createDate": "Nov 14, 2017 10:20:57 PM",       "lastOpDate": "Nov 14, 2017 10:20:57 PM"     }   ] }

Management IP

ZStack management nodes use management IP addresses to reach the operating systems (hypervisors) of hosts. Whether the management IP addresses will be used or not depends on the hypervisor types.

For example, in VMware, the official method to access an ESXi host is to use the vCenter server. In this regard, the management IP address will not be used.
However, in KVM, ZStack uses a management IP address to deploy an agent to the Linux operating system.

Management Network

A management network is used to manage and control the corresponding physical resources, such as a host, backup storage, and primary storage, of whose resources can be reached by using an IP address.

ZStack management nodes need to send commands to hosts and other appliances through the management networks. In this regard, the Linux servers that run ZStack management nodes must be able to access management networks.
Management networks will be used when it comes to appliance VMs. For the current ZStack version, the appliance VMs are vRouters or VPC vRouters.

State

A host has the following three states:

Enabled
Indicates that VM instances can be created and started on, or migrated to the host.
Disabled:
Indicates that VM instances cannot be created or started on, or migrated to the host.
Maintenance:
Indicates that the host is in maintenance mode.

Note:

PreMaintenance:

Indicates that a host is entering maintenance mode, as shown in Maintenance Mode.

The state transition diagram of a host is shown in Host State Transition Diagram.

Maintenance Mode

You can place a host in maintenance mode when you carry out some maintenance jobs, such as the installation of more memories. When a host is in maintenance mode, neither API operations nor ZStack internal tasks can be performed on the host. That is, tasks such as starting VM instances (API), stopping VM instances (API), and mounting primary storages (internal) cannot be performed on the host. ZStack defines maintenance mode into two states: PreMaintenance and Maintenance. The sequence that a host enters maintenance mode is as follows:

The state of a host is changed to PreMaintenance. At this stage, ZStack will attempt to migrate all VM instances running on the host to other appropriate hosts. If the migration fails, ZStack will stop those VM instances.
After all VM instances are migrated successfully or stopped, ZStack will change the state of the host to Maintenance. Then, you can perform maintenance jobs on the host.

After the maintenance jobs are completed, you can take a host out of Maintenance mode by placing it to Enabled or Disabled state.

Status

The status of a host indicates the command channel status between a host and a management node. In ZStack, a command channel is the method that a ZStack management node communicates with and notifies a host to perform related operations. The following examples are about the command channel:

In KVM, command channels are HTTP connections between ZStack management nodes and Python agents running on hosts.
In VMware, command channels are connections between vCenter servers and ESXi hosts.

A host has the following three statuses:

Connecting:
Indicates that a ZStack management node is trying to establish a command channel between the node itself and the host. At this stage, you cannot perform any operation on the host.
Connected:
Indicates that the command channel between a ZStack management node and the host is successfully established. At this stage, you can perform operations on the host. Only in this status, a host can be used to start or create VM instances.
Disconnected:
Indicates that the command channel between a ZStack management node and the host is lost. At this stage, you cannot perform any operation on the host.

When a ZStack management node starts, a command channel to a host will be established.

At this stage, the status of the host is Connecting.
After the command channel is successfully established, the status of the host will be changed to Connected.
If ZStack management node fails to establish the command channel, or the command channel is lost at a period of time, the status of the host to which the command channel connects will be changed to Disconnected.
ZStack management nodes will periodically send ping commands to hosts to check the health status of command channels. Once a host fails to respond, or a ping command times out, the status of the host will be changed to Disconnected.

The status transition diagram of a host is shown in Diagram for Host Connection Status Transition.

Figure 2. Host Status Transition Diagram

State and Status

The states have no direct relation to the statuses. States represent your decisions on a host, while statuses represent the communication condition of a host.