Five Ways To Maximize Your VMware vSphere VM Templates
One of the true measures of virtualization sophistication is the ability to have very specific configuration for your needs. When it comes to leveraging the virtual machine template technology, this is a great way to ensure every VM has a prescribed precise configuration. Here is a list of 5 specific VM configuration entries you may want to put in your vSphere VM templates:
1. Enable Changed Block Tracking
VMware has so many features to run VMware virtual machines, you should ensure that your VMs take advantage of it. One feature is Changed Block Tracking (CBT). CBT allows any application that reads the disks (usually in a backup situation) to read them all once, then leverage a report from vSphere that tells them what regions of the VMDK have changed since the last time the disks were read at that level. VMware KB 1020128 explains how to enable CBT and it is shown in the figure below:
Figure 1 – Enabling Change Block Tracking (CBT) in a vSphere Virtual Machine
2. Enable VMware Tools Upgrades During Power Cycle
Let’s face it, nobody likes going into VMs and ensuring that VMware Tools is up to date. We also don’t like the warning that tools is out of date in the vSphere Client and Web Client. A VM can be set to automatically update Tools during power cycles. This is not an in-guest reboot, but only during a power cycle. The logic behind this is that you don’t get into a situation where you are using the power button unless it is some form of maintenance anyways. Granted, this may cause an additional boot during troubleshooting interventions; but once VMware Tools are up to date the latest release should be very good about reboots into the future. This options is shown in the figure below:
Figure 2 – Enabling a VM to Upgrade VMware Tools During Power Cycle
3. Configure In-Guest Administration
It sounds out of place, but one of the things we can’t forget when we administer VMs is the ability to fully support them, including the guest operating system. One support measure would be a local service account. In the Windows operating system realm; this could include a local system account that is not a member of the Active Directory domain. Even if we have virtual console access, it may not do us any good if we can’t log in there either.
4. Remove Unnecessary Hardware
When it comes to VMs today, I never find myself using virtual floppy drives. I do leave the virtual optical drive, CD/DVD drive in each VM however. We are getting close to possibly removing the optical drive as well, as many virtual machines can natively ready .ISO images. VMs with ISO or virtual disk mappings can prohibit DRS rules from fully taking place or even block migration command such as vMotion. For now, we still should leave CD/DVD drives on VMs; but that may change.
5. Provision Resources Accordingly – Even if that Means Two Templates
I’ve seen a number of environments have templates for an operating system configured three different ways, such as small, medium and large. This way, specific configuration like disk geometry can be set correctly with each template deployment. While that configuration checkbox to edit the virtual machine hardware is indeed tempting; it’s better to stick to the prescribed and verified configuration. Besides, this opens to the door to configuration drift. It wouldn’t be very fun if the “large” VM existed in 3 or 4 different ways; such as 1 TB, 1022 GB and 1.1 TB for the primary operating system VMDK across three different VMs. I don’t know about you, but that seeing those types of configuration drift irritate me to no end.
What specific template configuration entities do you ensure your templates have? Share your comments below.