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Tutorial: Part-2 : How to Manage EVC using vSphere Python SDK pyVmomi?

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In part-1, we explored EVC enable, disable APIs & some important EVC properties using pyVmomi. In part-2, we would explore left out EVC APIs from part-1 i.e.CheckConfigureEvcMode_Task() & CheckAddHostEvc_Task(). In addition, we will also take a look at some more important EVC properties required to manage EVC end to end.

1. Checking whether EVC can be configured on existing cluster or not?
CheckConfigureEvcMode_Task() is responsible for checking exactly the same. If you have existing cluster with several hosts and if you would like to evaluate whether EVC can be enabled on cluster or not on particular EVCMode key, this API is really handy. If it is not possible to enable EVC on particular cluster, this API will return not only the set of reasons why it can fail to configure EVC but also the set of hosts those are causing it to fail. Before we start, below are the set of hosts present in cluster already.

vmware@localhost:~$ python getMaxEVCModeonHost.py
ClusterName::vThinkBVMCluster
10.160.20.30::intel-broadwell
10.160.20.31::intel-sandybridge
vmware@localhost:~$

To start with, the way we did in part-1, we will check whether EVC can be enabled on “intel-broadwell” EVCMode key. As we learned in last post, EVC should not be able to configure on this cluster with EVCMode “intel-broadwell”. Let us see whether API properly returns right reason and host that is causing it.

Below script is available on my git-hub repo as well

[python]
from pyVim.connect import SmartConnect, Disconnect
from pyVmomi import vim
import atexit
import ssl
import sys
import time

#Script to check whether EVC can be enabled on cluster with given EVCMode

s=ssl.SSLContext(ssl.PROTOCOL_TLSv1)
s.verify_mode=ssl.CERT_NONE
si= SmartConnect(host="10.160.50.60", user="Administrator@vsphere.local", pwd="VMware#12",sslContext=s)
content=si.content
cluster_name="vThinkBVMCluster";

# Below method helps us to get MOR of the object (vim type) that we passed.
def get_obj(content, vimtype, name):
obj = None
container = content.viewManager.CreateContainerView(content.rootFolder, vimtype, True)
for c in container.view:
if name:
if c.name == name:
obj = c
break
else:
obj = None
return obj

#Cluster object
cluster = get_obj(content,[vim.ClusterComputeResource],cluster_name)
evc_cluster_manager=cluster.EvcManager()

print "ClusterName::"+cluster.name

task=evc_cluster_manager.CheckConfigureEvcMode_Task("intel-broadwell")
time.sleep(5)
checkResult= task.info.result

if(checkResult):
print "EVC can not be enabled on this cluster, please take look at below reasons and hosts causing this issue"
for result in checkResult:
print result.error.msg
for h in result.host:
print h.name
print "———————"
else:
print "EVC can be successfully enabled on the cluster with no issues"

atexit.register(Disconnect, si)

[/python]

vmware@localhost:~$ python checkEVC.py
ClusterName::vThinkBVMCluster
EVC can not be enabled on this cluster, please take look at below reasons and hosts causing this issue
The host’s CPU hardware does not support the cluster’s current Enhanced vMotion Compatibility mode. The host CPU lacks features required by that mode.
10.160.20.31
———————

isn’t this error matching with this screenshot from Part-1?

Note: If you notice on line #38, CheckConfigureEvcMode_Task() API returns ClusterEVCManagerCheckResult only when EVC can NOT be configured on the cluster.

Now I did powerON one of the VMs on host, which has max EVCMode as “intel-broadwell” and executed above script but this time passed EVCMode key as “intel-sandybridge”. Let us take a look at output.

Output:
vmware@localhost:~$ python checkEVC.py
ClusterName::vThinkBVMCluster
EVC can not be enabled on this cluster, please take look at below reasons and hosts causing this issue
The host cannot be admitted to the cluster’s current Enhanced vMotion Compatibility mode. Powered-on or suspended virtual machines on the host may be using CPU features hidden by that mode.
10.160.20.30
———————
vmware@localhost:~$

You can see, EVC configuration failed since one of VM was powered ON, which is using some cpu features those are NOT available on “intel-sandybridge” EVC mode. This is expected and error is exactly matching with web client screenshot from Part-1.

Now I powered-off the VM residing on “intel-broadwell” based host & Powered-ON VM on host, which support max EVCMOde as “intel-sandybridge”. Finally executed same checkEVC.py script and below is the output.

Output:
vmware@localhost:~$ python checkEVC.py
ClusterName::vThinkBVMCluster
EVC can be succesfully enabled on the cluster with no issues
vmware@localhost:~$

wasn’t output cool? Note that VM was up on host with “intel-sandybridge” host and EVCMode used was also “intel-sandybridge”, hence EVC will be configured successfully. Now let us move on to next EVC API.

2. Checking whether host can be added into existing EVC enabled cluster or not?
CheckAddHostEvc_Task() API allows user to check exactly the same. This API accepts HostSpec as paramter for the host to be checked and below is the code snippet. I will leave it to you in order to try this API in your environment.

[python]
host_conn_spec=vim.host.ConnectSpec()
host_conn_spec.force=True
host_conn_spec.hostName=host.name
host_conn_spec.userName=host_user
host_conn_spec.password=host_pass
thumb_print=host.summary.config.sslThumbprint
host_conn_spec.sslThumbprint=thumb_print
print host_conn_spec
task=evc_cluster_manager.CheckAddHostEvc_Task(host_conn_spec)
[/python]

That is all about EVC APIs. I hope Part-1 & Part-2 have given you good insight into how to play around EVC APIs. Stay tuned for my next post. Please comment if you have any query.