VirtuBytes

Bytes of virtualization with bits of other technology.

How to Downgrade/Roll Back ESXi 6.5

Occasionally, an issue or bug will require admins to revert to a previous build or version of ESXi. In the event you patch your hosts (as opposed to fresh installs), it is possible to rollback to a prior installed version via the GUI. Rollbacks should not be taken lightly. If you are reverting in a production environment, discuss options with support first.

A few housekeeping items before we jump into the rollback process.

Compatibility – If you are leveraging new features introduced in vSphere 6.5, ensure you check compatibility against vSphere 6.0. Two main features to be cognizant of when reverting from 6.5 to 6.0 are VMFS and virtual machine hardware versions.

  • VMFS 6: VMFS 6 was introduced with vSphere 6.5. However, vSphere 6.0 utilized VMFS 5. If you created a VMFS 6 version with ESXi 6.5, you will not be able to access the datastore after rollback.
  • VM Hardware Version: vSphere 6.5 also introduced version 13 virtual machine hardware. Version 13 hardware is not compatible with ESXi 6.0. Version 11 or lower is compatible.

Back Up Host Configuration – Before making any changes, back up the ESXi Configuration.

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Install Nested ESXi 6.5 on Ravello

Recently, I had the opportunity to test a nested lab deployment on Oracle’s Ravello Cloud Service. If you are unfamiliar with Oracle’s Ravello offering, it enables you to deploy your VMware or KVM workloads on Oracle Public Cloud, AWS, or Google Cloud. Ravello seamlessly runs your environment on top of their own nested hypervisor, HVX. HVX, in turn, is run on resources provisioned by Oracle, AWS, or Google Cloud. Utilizing Ravello’s HVX hypervisor allows the underlying cloud infrastructure to behave like your traditional datacenter; thus, enabling you to run your VMware workloads without modification.

Due to additional layers of abstraction, nested environments are prone to performance bottlenecks compared to bare metal offerings like VMware Cloud on AWS. To address this issue, Oracle recently announced the ability to run HVX on top of bare metal servers with the Oracle Cloud Infrastructure (OCI); therefore, eliminating a layer of abstraction.

Ravello on OCI or AWS/Google Cloud

Depending on the cloud region used for deployment, one of three nested virtualization approaches are used for running your workload; software-assisted, hardware-assisted, and direct on bare metal.

Software-assisted nested virtualization is Ravello’s traditional approach to running workloads on AWS or Google Cloud. In these instances, the underlying hardware virtualization extensions are not typically exposed to Ravello. Therefore, HVX uses binary translation with direct execution to run workloads.

Hardware-assisted nested virtualization leverages exposed virtualization extensions on the underlying cloud hardware. Running on Oracle’s Cloud Infrastructure (OCI), HVX has complete access to these hardware extensions, which increases performance over software-assisted nested virtualization.

Oracle Cloud Infrastructure (OCI) also supports the ability to run directly on bare metal servers. This results in increased performance as there is no need for any additional software or hardware translations.

Regardless of region or performance, Ravello provides a variety of use-cases for your workloads including development, testing, sales demos, POCs, and even VCAP lab preparations.

In this post, we are going to install VMware ESXi 6.5 on Ravello’s Cloud Service for testing purposes. The ability to run additional hypervisors (Nested²) such as VMware ESXi, KVM, or Hyper-V is beneficial in testing or lab prep scenarios.

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Reset vCenter SSO Administrator Password vSphere 6.5

By default, the vCenter Single Sign-On password expires every 90 days. To prevent unexpected expiration, the vSphere Client issues a warning when the password is about to expire; however, if you find yourself in a situation where you cannot recall the password or the password has expired, it can be reset. The reset process is performed from an SSH session to vCenter.

Reset SSO Administrator Password

To begin, SSH to the vCenter Server Appliance and log in with the root account.

vCenter Root Log In

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Manually Configure ESXi Syslog Location

All VMware hosts run a service for logging system information. This service, vmsyslogd, logs messages from the VMkernel and other system components for auditing and diagnostic purposes. By default, the logs are directed to a local scratch location or ramdisk. The scratch space is created automatically during ESXi installation in the form of a 4 GB Fat16 local scratch partition. If storage space is unavailable, the host will store data on a ramdisk, which is not persistent across reboots. That being the case, many admins choose to send these logs to a persistent datastore or remote logging server for retention.

Configuring the log location can be done in a variety of ways. In this post, we will focus on vSphere Web Client and ESXi Shell.

Manually Configure ESXi Syslog – vSphere Web Client

For convenience sake, the Web Client is popular for setting the log location. In the Web Client, the Syslog.global.logdir key controls the syslog location. By default, the location is set to []/scratch/log which references that local scratch location created during installation or ramdisk. To change the syslog location, navigate to Advanced System Settings under the host Configuration tab. Edit the Syslog.global.logdir value to specify the new log path. Format the value as [datastore]/logdir. Example: [DevDS]/LOGS/Dev

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Identify NIC Driver and Firmware Versions with ESXCLI

Quick byte today – Last week, we discussed an HPE advisory affecting certain network adapters on VMware hosts.  The advisory pertained to specific firmware and driver versions. If you need to identify or verify such network card information, it is possible to pull that data via ESXCLI commands. In this post, we will get a list of installed NICs as well as individual driver and firmware versions.

First, let’s get a list of the installed NICs. To do so, SSH to the pertinent host and run the esxcli network nic list command. Here we can see a record of devices and general information.

esxcli network nic list

ESXCLi NIC List

Now that we have a list of the installed NICs, we can pull detailed configuration information. Run the esxcli network nic get command specifying the name of the NIC necessary.

esxcli network nic get –n vmnic0

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