PSC’s fail to join Domain after Upgrade from vSphere 6.0 U2 to 6.0 U2b or 6.0U3b

Recently, I have come across an issue with the PSC’s not joining to the domain (They disconnected from the domain automatically) after upgrading the vCenter components (PSC01, PSC02 and vCenter windows server) from 6.0 Update 2 build 3634791 to 6.0 Update 2a build 4632154 or to 6.0 Update 3b build 5326079. This issue occurred as the windows domain controller was 2012 R2 and SMB 2 was the communication protocol to the domain controller. we have to enable SMB 2 on the PSC’s for them to communicate to the domain after the Upgrade.

here is the process to enable SMB2 on the PSC’s —

login to PSC01 and run the following command to check the values

/opt/likewise/bin/lwregshell list_values '[HKEY_THIS_MACHINE\Services\lwio\Parameters\Drivers\rdr]'

check the value of “Smb2Enabled”, this value will be 0, we will need to change it to 1 to enable it.

change SMB2 to be Enabled

/opt/likewise/bin/lwregshell set_value '[HKEY_THIS_MACHINE\Services\lwio\Parameters\Drivers\rdr]' Smb2Enabled 1

Once enabled, we need to restart the service lwio

/opt/likewise/bin/lwsm restart lwio

Check the values again —

/opt/likewise/bin/lwregshell list_values '[HKEY_THIS_MACHINE\Services\lwio\Parameters\Drivers\rdr]'

This time the value of “Smb2Enabled” will be 1.

This process is repeated for PSC02 as well and once this is done on both the PSC’s, you can go ahead and add the PSC’s to the domain and the function works !!

The process to change the SMB value on ESXi 6.0 is a little different and here are the commands —

Check values —

/usr/lib/vmware/likewise/bin/lwregshell list_values ‘[HKEY_THIS_MACHINE\Services\lwio\Parameters\Drivers\rdr]’

Change SMB2 to be enabled

/usr/lib/vmware/likewise/bin/lwregshell set_value ‘[HKEY_THIS_MACHINE\Services\lwio\Parameters\Drivers\rdr]’ SMB2Enabled 1

Restart lwio service

/usr/lib/vmware/likewise/bin/lwsm restart lwio

 

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Disable vSphere Managed Object Browser (MOB)

To harden your ESXi 6.0 hosts, we disable the MOB service so that any attacker can’t get to the web browser and access the MOB of the ESXi host (ex: https://esxi01.lab.com/mob), this setting will disable one of the attack vectors of theESXi hosts in the environment.

to do this, you SSH into the ESXi host where you want to disable the mob service and perform the following commands

esxi01# vim-cmd proxysvc/remove_service "/mob" "httpsWithRedirect"

to verify if the mob service has been removed from the ESXi host, use the following command

esxi01# vim-cmd proxysvc/service_list

the above command will list all the services on the ESXi host, look for the service “/mob”, if you don’t see this service, then it has been removed. if it is still there, then you will have to perform the first command and reboot the ESXi host to disable the mob service from the host.

 

 

Can’t fork error on ESi 6 host on UCS Blade

Recently, I was working on an UCS blade firmware upgrade along with esxi upgrade from esxi 5.5 to 6.0 and came across this error where the esxi host became unresponsive with an error “can’t fork” on its DCUI.

here is a little background on this story, this particular blade was B240 blade which was being used as SAP HANA blade by the customer and the firmware upgrade and esxi upgrade went fine and two days later the host became unresponsive and we couldn’t connect to it using SSH, DCUI, etc, connecting to the kvm console revealed the below screen when we went to its Alt+F1 command interface

Esxi_Cant_fork_error

we had to bounce the box and we had to reduce the linux vm memory which was hosting SAP HANA on it to be 10% less than the memory of the esxi host.

Conclusion: The HANA VM (linux) on the esxi host should have 10% less memory than the overall memory of the esxi host to avoid this problem.

How to Install Cisco VEM vib on an ESXi 6 host

Recently, I had to install the Cisco vem module onto an esxi 6 host as it was not installed and i couldn’t join the esxi host to the cisco nexus 1000v distributed switch. here is the process on how to first check if the vem module is installed on the esxi host.

SSH into the esxi host and run the following commands to check if the VEM module is installed

host# esxcli software vib list | grep -i vem

the above command will display the cisco vem module installed on the esxi host, if nothing is displayed then you will have to install the vem module by downloading the vem vib from the nexus 1kv in the environment.

i did it by going to https://nexus1kv_hostname    in a web browser which will display you the vibs which you can download from nexus 1000v, download the vem vib associated with your environment and run the following command to install the vib onto the esxi host

upload the vem vib file onto a datastore on the host

SSH into the esxi host where you want to install the vem module

host# esxcli software vib install -v /vmfs/volumes/<directory_path>/cross_cisco-vem-version_x.x.x.x.x.vib

NOTE: directory_path in the above command is the place where the cisco vem vib is stored. (name of the datastore/volume)

Once the vib is installed you can check the status of the vem by using the command

host# vem status

The above command will display that the VEM agent (vemdpa) is running