VMware administration and management can be complicated and frustrating. But it's much easier when you know the...
optimal way to handle virtual machines (VMs).
VMware administration and management requires not only technical expertise but also problem-solving skills. And if you don't properly manage a VMware environment, it can quickly come back to bite you. These VMware administration and management tips will help you better manage your VMs and avoid common mistakes.
VMware administration tip No. 1: Thin is in
You should strive to properly size virtual disks, but sometimes disk size grows, such as with a database server that accumulates additional data on a regular basis.
In these situations, administrators often allocate more disk space to a VM than is initially needed. Thin provisioning helps reduce this wasted space.
Thin-provisioned disks do not allocate the full virtual disk size when created. Instead, they grow as disk blocks are written inside the guest operating systems.
Thin provisioning can be done at both the virtualization and storage-array levels, so which method should you choose? The answer is both. You get better space efficiency, and they operate independently, so they will not conflict with each other. You can also use Storage vMotion to re-shrink disks at the virtualization level when needed.
VMware administration tip No. 2: Install and update VMware Tools
Sure, VMs can run without VMware Tools installed inside the guest OS, but they won't run as efficiently. Aside from its management tools, VMware Tools also contains virtual hardware drivers that are better optimized and more efficient than the default drivers in the OS.
Additionally, VMware Tools enables communication between a hypervisor and the guest OS, which helps optimize a guest OS to run on a virtual host. After you upgrade a host, keep VMware Tools up to date. New versions may include new drivers and security enhancements that are critical for optimum performance.
VMware administration tip No. 3: Monitor and limit VM snapshots
You should not rely on VM snapshots as a primary backup method. Snapshots are best for ad hoc backups when performing OS and application maintenance and upgrades.
When snapshots are running, they have some resource overhead, which can limit feature capabilities. They also create the potential for problems as your single virtual disk is split into two or more virtual disk files.
It's best to delete snapshots as soon as you don't need them, because it's easy to forget that snapshots are running, and you may not discover them until months later. At that point, snapshots will have grown extremely large, and deleting them takes a long time, which can cause poor VM performance.
Additionally, snapshots can eat up a lot of disk space on data stores. Therefore, you should run periodic reports and use reporting and management tools and alarms to keep track of this disk usage. The new Storage View in vCenter Server also has a snapshot size column, which makes it easy to monitor snapshot usage.
VMware administration tip No. 4: Use templates and clones
The ability to create templates and clone VMs are big benefits of virtualization. Both actions can make new VM deployments simple and easy.
Templates are standard VM images you can use to create new VMs with just a few clicks of the mouse. Cloning, on the other hand, makes an identical copy of an existing VM, which is useful for creating new VMs and troubleshooting.
VMware administration tip No.5: Deal with rogue VMs
Sometimes VMs go into a "zombie state" and can't be powered off. On a physical server, you can yank the power cord to reset a hung server. But VMs don't have power cords, so that's not an option. If you reboot the host to reset a VM, you'll disrupt the other VMs on the host.
Fortunately there are some brute-force methods that you can use from the host's management console to reset a VM without powering off the host. But these methods differ for ESX- and ESXi-based hosts.
About the expert
Eric Siebert is a 25-year IT veteran with experience in programming, networking, telecom and systems administration. He is a guru-status moderator on the VMware community VMTN forums and maintains vSphere-land.com, a VMware information site.