vSphere Host Profiles: Using Customization Files

Overview

If you own vSphere Enterprise Plus licences, using vSphere Host Profiles is a no brainer. Even if you rarely add ESXi hosts to your cluster, why configure them by hand if you can do that by a few mouse clicks in a fast and consistent manner.

Host profiles are usually created by setting up one ESXi host according to your requirements and then capturing its state. Some settings in a host profile are unique to each host, which include the host name, VMkernel adapter network settings, user name for joining host to AD, etc. When you apply your profile to a new unprepared host, vCenter will ask you to specify these settings. This step is called host customization.

You can either type these settings manually or if you want to take your automation game one step further, you can use a customization file, which is simply the list of setting in .csv format.

This feature was first introduced in vSphere 6.5 and official documentation is a bit light on this topic. Purpose of this post is to close this gap by demonstrating where to find this configuration option.

Create

To create a customization file, right click on a ESXi host and choose Host Profiles > Export Host Customizations. This host has to have host profile already applied to it (including all customization settings), otherwise this option will be grayed out. This can be the first host you used to capture the original host profile.

Open .csv file in your editor of choice and change settings accordingly. If you adding multiple hosts to your cluster, you can write a script to generate multiple copies of this file for each new ESXi host you’re adding.

Apply

Host customization settings are specified (manually or using a customization file) when host profile is being applied to the host. So first right click on the host and choose Host Profiles > Attach Host Profile. Then on Customize hosts page import customization file by clicking on the Browse button:

Note: If you hit the “Host settings validation failed” error after applying host customizations, read my blog article here that explains the problem.

Conclusion

Pretty simple, isn’t it? Key is to not forget that customization file can be specified either when you are applying host profile or, alternatively, you can skip host customization step and use Host Profiles > Edit Host Customizations later. For host that doesn’t have a host profile associated with it, Edit Host Customizations option will always be greyed out.

Advertisement

Quick Way to Migrate VMs Between Standalone ESXi Hosts

Introduction

Since vSphere 5.1, VMware offers an easy migration path for VMs running on hosts managed by a vCenter. Using Enhanced vMotion available in Web Client, VMs can be migrated between hosts, even if they don’t have shared datastores. In vSphere 6.0 cross vCenter vMotion(xVC-vMotion) was introduced, which no longer requires you to even have old and new hosts be managed by the same vCenter.

But what if you don’t have a vCenter and you need to move VMs between standalone ESXi hosts? There are many tools that can do that. You can use V2V conversion in VMware Converter or replication feature of the free version of Veeam Backup and Replication. But probably the easiest tool to use is OVF Tool.

Tool Overview

OVF Tool has been around since Open Virtualization Format (OVF) was originally published in 2008. It’s constantly being updated and the latest version 4.2.0 supports vSphere up to version 6.5. The only downside of the tool is it can export only shut down VMs. It’s may cause problems for big VMs that take long time to export, but for small VMs the tool is priceless.

Installation

OVF Tool is a CLI tool that is distributed as an MSI installer and can be downloaded from VMware web site. One important thing to remember is that when you’re migrating VMs, OVF Tool is in the data path. So make sure you install the tool as close to the workload as possible, to guarantee the best throughput possible.

Usage Examples

After the tool is installed, open Windows command line and change into the tool installation directory. Below are three examples of the most common use cases: export, import and migration.

Exporting VM as an OVF image:

> ovftool “vi://username:password@source_host/vm_name” “vm_name.ovf”

Importing VM from an OVF image:

> ovftool -ds=”destination_datastore” “vm_name.ovf” “vi://username:password@destination_host”

Migrating VM between ESXi hosts:

> ovftool -ds=”destination_datastore” “vi://username:password@source_host/vm_name” “vi://username:password@destination_host”

When you are migrating, machine the tool is running on is still used as a proxy between two hosts, the only difference is you are not saving the OVF image to disk and don’t need disk space available on the proxy.

This is what it looks like in vSphere and HTML5 clients’ task lists:

Observations

When planning migrations using OVF Tool, throughput is an important consideration, because migration requires downtime.

OVF Tool is quite efficient in how it does export/import. Even for thick provisioned disks it reads only the consumed portion of the .vmdk. On top of that, generated OVF package is compressed.

Due to compression, OVF Tool is typically bound by the speed of ESXi host’s CPU. In the screenshot below you can see how export process takes 1 out of 2 CPU cores (compression is singe-threaded).

While testing on a 2 core Intel i5, I was getting 25MB/s read rate from disk and an average export throughput of 15MB/s, which is roughly equal to 1.6:1 compression ratio.

For a VM with a 100GB disk, that has 20GB of space consumed, this will take 20*1024/25 = 819 seconds or about 14 minutes, which is not bad if you ask me. On a Xeon CPU I expect throughput to be even higher.

Caveats

There are a few issues that you can potentially run into that are well-known, but I think are still worth mentioning here.

Special characters in URIs (string starting with vi://) must be escaped. Use % followed by the character HEX code. You can find character HEX codes here: http://www.techdictionary.com/ascii.html.

For example use “vi://root:P%40ssword@10.0.1.10”, instead of “vi://root:P@ssword@10.0.1.10” or you can get confusing errors similar to this:

Error: Could not lookup host: root

Disconnect ISO images from VMs before migrating them or you will get the following error:

Error: A general system error occurred: vim.fault.FileNotFound

Conclusion

OVF Tool requires downtime when exporting, importing or migrating VMs, which can be a deal-breaker for large scale migrations. When downtime is not a concern or for VMs that are small enough for the outage to be minimal, from now on OVF Tool will be my migration tool of choice.