VMWare ESXi is very powerful when it comes to virtual technology. I have worked with both Hyper-V and VMWare in the past and it is fair to say that VMWare knows what they are doing. In this post I am going to discuss a couple key features of VMWare, stuff that you may not know.
With Hyper-V you have the option to dynamically increase the memory allocation up to a fixed value. Let’s say you have a VM that you want to start out only using 512 MB and ramp up to 2 GB when needed, this is fairly straight forward with Hyper-V. With VMWare, things are not as straight forward, but there are added benefits. VMWare ESXi has the ability to share common memory with other VM’s. For example, you are running a bunch of Windows Server 2012 R2 VM’s, most of them share the same memory as the others. Let’s say you have three VM”s running that same OS, each one has the same core memory usage for the OS, let’s say 256 MB. ESXi can learn over time and begin to share the core memory junks. You can see this when you first start a VM you notice the memory is in high usage, then after some time it tends to taper off and then eventually it will read a really low number. This is shared memory at work, ESXi has learned that the VM doesn’t need 1 GB of memory to function and that there are other VM’s with similar memory junks. Overall, you can squeeze more VM’s onto you host.
Now let’s get into how to configure memory shares, which isn’t that bad.
- Make sure the VM you want to edit is turned off.
- On a VM that you have already created, go to edit settings.
- Expand the memory section.
- You should now have options for reservation, limit, and shares. This is where we are going to make our changes.
- Shares is what you will specify that will allow ESXi to share the memory between VM’s. You can leave it set to Normal or give it a different value, I set mine to High, to use as much as possible.
- Next, set the reservation, which is the minimum value you want you VM to start with.
- Next, set the limit, this is the maximum value you want your VM to expand to.
- Save your settings
- Start you VM, you will not notice the changes right away. The changes may not happen until more VM’s are configured and started.
Memory shares are a nice and easy way to consolidate memory from common VM’s and may allow you to expand you inventory more.
Virtual Networking vNetwork
As you can virtualize physical machines, you can virtualize physical switches. vNetworks can be configured on a single ESXi host or across multiple ESXi hosts, this allows you to be very flexible with your configurations. Just as you can configure a switch, you can configure virtual NICs for your VM’s. Virtual NICs act just like a physical NIC. A single VM can have up to 10 NICs installed, with their own IP and MAC address, this makes the VM indistinguishable from the rest of network. VMWare ESXi vNetwork has all the features of physical network such as VLANs, port configuration policies, VLAN tagging, layer 2 security policies, and NIC teaming. Having an entire virtual network at your fingertips has not been any easier.
A few applications I use vNetwork for are segregation of production, development, and testing networks. This allows everything to safe on one network while I can break another. I also have a seperate network where I can switch VM’s to in the event an attack or virus happens. Having these networks setup in a virtual enviroment has made life a little easier and less messy when it comes to cabling. The added benefit is that I can configure and change the configuration from any where.
The two mentioned features is just the tip of the ice berge, there are many more features that your enviroment may benefit from. I will continue to post about various features of VMWare and how others compare.