Managing Hosts 4.0

In order to use your existing physical nodes, you have to add them to the system as OpenNebula hosts. You need the following information:

Hostname of the host or IP
Information Driver to be used to monitor the host, e.g. kvm. These should match the Virtualization Drivers installed and more info about them can be found at the Virtualization Subsystem guide.
Virtualization Driver to boot, stop, resume or migrate VMs in the host, e.g. kvm. Information about these drivers can be found in its guide.
Networking Driver to isolate virtual networks and apply firewalling rules, e.g. 802.1Q. Information about these drivers can be found in its guide.
Cluster where to place this host. The Cluster assignment is optional, you can read more about it in the Managing Clusters guide.

Before adding a host check that you can ssh to it without being prompt for a password

inlinetoc

onehost command

The following sections show the basics of the onehost command with simple usage examples. A complete reference for these commands can be found here.

This command enables Host management. Actions offered are:

create: Creates a new Host
delete: Deletes the given Host
enable: Enables the given Host
disable: Disables the given Host
update: Update the template contents.
sync: Synchronizes probes in all the hosts.
list: Lists Hosts in the pool
show: Shows information for the given Host
top: Lists Hosts continuously
flush: Disables the host and reschedules all the running VMs it.

Create and Delete

Hosts, also known as physical nodes, are the serves managed by OpenNebula responsible for Virtual Machine execution. To use these hosts in OpenNebula you need to register them so they are monitored and well-known to the scheduler.

Creating a host:

<xterm> $ onehost create host01 –im dummy –vm dummy –net dummy ID: 0 </xterm>

The parameters are:

--im/-i: Information Manager driver. Valid options: kvm, xen, vmware, ec2, ganglia, dummy.
--vm/-v: Virtual Machine Manager driver. Valid options: kvm, xen, vmware, ec2, dummy.
--net/-n: Network manager driver. Valid options: 802.1Q,dummy,ebtables,fw,ovswitch,vmware.

To remove a host, just like with other OpenNebula commands, you can either specify it by ID or by name. The following commands are equivalent:

<xterm> $ onehost delete host01 $ onehost delete 0 </xterm>

Show, List and Top

To display information about a single host the show command is used: <xterm> $ onehost show 0 HOST 0 INFORMATION ID : 0 NAME : host01 CLUSTER : - STATE : MONITORED IM_MAD : dummy VM_MAD : dummy VN_MAD : dummy LAST MONITORING TIME : 07/06 17:40:41

HOST SHARES TOTAL MEM : 16G USED MEM (REAL) : 857.9M USED MEM (ALLOCATED) : 0K TOTAL CPU : 800 USED CPU (REAL) : 299 USED CPU (ALLOCATED) : 0 RUNNING VMS : 0

MONITORING INFORMATION CPUSPEED=“2.2GHz” FREECPU=“501” FREEMEMORY=“15898723” HOSTNAME=“host01” HYPERVISOR=“dummy” TOTALCPU=“800” TOTALMEMORY=“16777216” USEDCPU=“299” USEDMEMORY=“878493” </xterm>

We can instead display this information in XML format with the -x parameter:

<xterm> $ onehost show -x 0 <HOST>

<ID>0</ID>
<NAME>host01</NAME>
<STATE>2</STATE>
<IM_MAD>dummy</IM_MAD>
<VM_MAD>dummy</VM_MAD>
<VN_MAD>dummy</VN_MAD>
<LAST_MON_TIME>1341589306</LAST_MON_TIME>
<CLUSTER_ID>-1</CLUSTER_ID>
<CLUSTER/>
<HOST_SHARE>
  <DISK_USAGE>0</DISK_USAGE>
  <MEM_USAGE>0</MEM_USAGE>
  <CPU_USAGE>0</CPU_USAGE>
  <MAX_DISK>0</MAX_DISK>
  <MAX_MEM>16777216</MAX_MEM>
  <MAX_CPU>800</MAX_CPU>
  <FREE_DISK>0</FREE_DISK>
  <FREE_MEM>12852921</FREE_MEM>
  <FREE_CPU>735</FREE_CPU>
  <USED_DISK>0</USED_DISK>
  <USED_MEM>3924295</USED_MEM>
  <USED_CPU>65</USED_CPU>
  <RUNNING_VMS>0</RUNNING_VMS>
</HOST_SHARE>
<TEMPLATE>
  <CPUSPEED><![CDATA[2.2GHz]]></CPUSPEED>
  <FREECPU><![CDATA[735]]></FREECPU>
  <FREEMEMORY><![CDATA[12852921]]></FREEMEMORY>
  <HOSTNAME><![CDATA[host01]]></HOSTNAME>
  <HYPERVISOR><![CDATA[dummy]]></HYPERVISOR>
  <TOTALCPU><![CDATA[800]]></TOTALCPU>
  <TOTALMEMORY><![CDATA[16777216]]></TOTALMEMORY>
  <USEDCPU><![CDATA[65]]></USEDCPU>
  <USEDMEMORY><![CDATA[3924295]]></USEDMEMORY>
</TEMPLATE>

</HOST> </xterm>

To see a list of all the hosts:

<xterm> $ onehost list

ID NAME            CLUSTER   RVM TCPU FCPU ACPU    TMEM    FMEM    AMEM STAT
 0 host01          -           0  800  198  800     16G   10.9G     16G on
 1 host02          -           0  800  677  800     16G    3.7G     16G on

</xterm>

It can also be displayed in XML format using -x:

<xterm> $ onehost list -x <HOST_POOL>

<HOST>
  ...
</HOST>
...

</HOST_POOL> </xterm>

The top command is similar to the list command, except that the output is refreshed until the user presses CTRL-C.

Enable, Disable and Flush

The disable command disables a host, which means that no further monitorization is performed on this host and no Virtual Machines are deployed in it. It won't however affect the running VMs in the host.

<xterm> $ onehost disable 0 </xterm>

To re-enable the host use the enable command:

<xterm> $ onehost enable 0 </xterm>

The flush command will mark all the running VMs in the specified host as to be rescheduled, which means that they will be migrated to another server with enough capacity. At the same time, the specified host will be disabled, so no more Virtual Machines are deployed in it. This command is useful to clean a host of running VMs.

<xterm> $ onehost list

ID NAME            CLUSTER   RVM TCPU FCPU ACPU    TMEM    FMEM    AMEM STAT  
 0 host01          -           3  800   96  500     16G   11.1G   14.5G on    
 1 host02          -           0  800  640  800     16G    8.5G     16G on    
 2 host03          -           3  800  721  500     16G    8.6G   14.5G on

$ onevm list

  ID USER     GROUP    NAME            STAT UCPU    UMEM HOST             TIME
   0 oneadmin oneadmin vm01            runn   54  102.4M host03       0d 00h01
   1 oneadmin oneadmin vm02            runn   91  276.5M host02       0d 00h01
   2 oneadmin oneadmin vm03            runn   13  174.1M host01       0d 00h01
   3 oneadmin oneadmin vm04            runn   72  204.8M host03       0d 00h00
   4 oneadmin oneadmin vm05            runn   49  112.6M host02       0d 00h00
   5 oneadmin oneadmin vm06            runn   87  414.7M host01       0d 00h00

$ onehost flush host02 $ onehost list

ID NAME            CLUSTER   RVM TCPU FCPU ACPU    TMEM    FMEM    AMEM STAT  
 0 host01          -           3  800  264  500     16G    3.5G   14.5G on    
 1 host02          -           0  800  153  800     16G    3.7G     16G off   
 2 host03          -           3  800  645  500     16G   10.3G   14.5G on

$ onevm list

  ID USER     GROUP    NAME            STAT UCPU    UMEM HOST             TIME
   0 oneadmin oneadmin vm01            runn   95  179.2M host03       0d 00h01
   1 oneadmin oneadmin vm02            runn   27  261.1M host03       0d 00h01
   2 oneadmin oneadmin vm03            runn   70    343M host01       0d 00h01
   3 oneadmin oneadmin vm04            runn    9  133.1M host03       0d 00h01
   4 oneadmin oneadmin vm05            runn   87  281.6M host01       0d 00h01
   5 oneadmin oneadmin vm06            runn   61  291.8M host01       0d 00h01

</xterm>

Update

It's sometimes useful to store information in the host's template. To do so, the update command is used.

An example use case is to add the following line to the host's template: <xterm> TYPE=“production” </xterm>

Which can be used at a later time for scheduling purposes by adding the following section in a VM template: <xterm> SCHED_REQUIREMENTS=“TYPE=\”production\“” </xterm>

That will restrict the Virtual Machine to be deployed in TYPE=production hosts.

Sync

When OpenNebula monitors a host, it copies a certain amount of files to /var/tmp/one. When the administrator changes these files, they can be copied again to the hosts with the sync command.

Take into account that this command is not synchronous. The files will get copied to the hosts the next time the IM (Information Manager driver) monitors the host.

Host Life-cycle

Short state	State	Meaning
`init`	`INIT`	Initial state for enabled hosts.
`update`	`MONITORING_MONITORED`	Monitoring a healthy Host.
`on`	`MONITORED`	The host has been successfully monitored.
`err`	`ERROR`	An error occurred while monitoring the host. See the Host information with `onehost show` for an error message.
`off`	`DISABLED`	The host is disabled, and won't be monitored. The scheduler ignores Hosts in this state.
`retry`	`MONITORING_ERROR`	Monitoring a host in error state.

Scheduler Policies

You can define global Scheduler Policies for all VMs in the sched.conf file, follow the Scheduler Guide for more information. Additionally, users can require their virtual machines to be deployed in a host that meets certain constrains. These constrains can be defined using any attribute reported by onehost show, like the architecture (ARCH).

The attributes and values for a host are inserted by the monitoring probes that run from time to time on the nodes to get information. The administrator can add custom attributes either creating a probe in the host, or updating the host information with: onehost update <HOST_ID>. Calling this command will fire up an editor (the one specified in the EDITOR environment variable) and you will be able to add, delete or modify some of those values.

<xterm> $ onehost show 3 […] MONITORING INFORMATION CPUSPEED=2.2GHz FREECPU=800 FREEMEMORY=16777216 HOSTNAME=ursa06 HYPERVISOR=dummy TOTALCPU=800 TOTALMEMORY=16777216 USEDCPU=0 USEDMEMORY=0

$ onehost update 3

[in editor, add CUSTOM_ATTRIBUTE=VALUE]

$onehost show 3 […] MONITORING INFORMATION CPUSPEED=2.2GHz FREECPU=800 FREEMEMORY=16777216 HOSTNAME=ursa06 HYPERVISOR=dummy TOTALCPU=800 TOTALMEMORY=16777216 USEDCPU=0 USEDMEMORY=0 CUSTOM_ATTRIBUTE=VALUE </xterm>

This feature is useful when we want to separate a series of hosts or marking some special features of different hosts. These values can then be used for scheduling the same as the ones added by the monitoring probes, as a placement requirement:

SCHED_REQUIREMENTS = "CUSTOM_ATTRIBUTE = \"SOME_VALUE\""

A Sample Session

Hosts can be added to the system anytime with the onehost command. You can add the hosts to be used by OpenNebula like this:

<xterm> $ onehost create host01 –im kvm –vm kvm –net dummy $ onehost create host02 –im kvm –vm kvm –net dummy </xterm>

The status of the hosts can be checked with the onehost list command:

<xterm> $ onehost list

ID NAME         CLUSTER     RVM   TCPU   FCPU   ACPU   TMEM   FMEM   AMEM STAT
 0 host01       -             7    400    290    400   3.7G   2.2G   3.7G   on
 1 host02       -             2    400    294    400   3.7G   2.2G   3.7G   on
 2 host03       -             0    400    312    400   3.7G   2.2G   3.7G  off

</xterm>

And specific information about a host with show:

<xterm> $ onehost show host01 HOST 0 INFORMATION ID : 0 NAME : host01 CLUSTER : - STATE : MONITORED IM_MAD : kvm VM_MAD : kvm VN_MAD : dummy LAST MONITORING TIME : 1332756227

HOST SHARES MAX MEM : 3921416 USED MEM (REAL) : 1596540 USED MEM (ALLOCATED) : 0 MAX CPU : 400 USED CPU (REAL) : 74 USED CPU (ALLOCATED) : 0 RUNNING VMS : 7

MONITORING INFORMATION ARCH=x86_64 CPUSPEED=2393 FREECPU=326.0 FREEMEMORY=2324876 HOSTNAME=rama HYPERVISOR=kvm MODELNAME=“Intel(R) Core(TM) i5 CPU M 450 @ 2.40GHz” NETRX=0 NETTX=0 TOTALCPU=400 TOTALMEMORY=3921416 USEDCPU=74.0 USEDMEMORY=1596540 </xterm>

If you want not to use a given host you can temporarily disable it:

<xterm> $ onehost disable host01 </xterm>

A disabled host should be listed with STAT off by onehost list. You can also remove a host permanently with:

<xterm> $ onehost delete host01 </xterm>

Detailed information of the onehost utility can be found in the Command Line Reference

Using Sunstone to Manage Hosts

You can also manage your hosts using Sunstone. Select the Host tab, and there, you will be able to create, enable, disable, delete and see information about your hosts in a user friendly way.