Have you ever gone to bed, and wondering what you might have started?
I had one of these thoughts earlier this week.
The reason for that is that I had a meeting with a large company. They are mainly focusing on hosting, and deliver ‘Virtual Private Servers’. They have 4 clusters and over 20 nodes, and runs over 150 VMs.
The one thing in common for those VMs, is that they are all Windows Servers (2003 R2, 2008, and mostly 2008 R2).
So I asked them: - Which hypervisor are you using?
The answer: - VMware
That got me started…
- Who runs VMware voluntary in 2011?
When I explained the licensing part of Windows Server 2008 R2 Datacenter – that gives you an unlimited numbers of VMs, they went quite silent for a while.
I actually served the” big shot” at the beginning and then followed up with some sort of a metaphor about parent/child-relationships, explaining the architecture of Hyper-V.
When you install the Hyper-V role in Windows Server 2008 R2, you cause the hypervisor to be installed between the physical hardware and the Windows kernel at system boot time. This turns the Windows installation into this special guest – the parent. The parent is still the boss when it comes to access to the hardware, but are responsible to provide additional services to the other partitions (child partitions/VMs). And since the child partitions are running Windows Server as well, you might be tempted to think that Windows knows what`s best for the VMs – just like you knows what`s best for your children – I said.
He got the point he said, and started to explain that they needed VMware to be able to have a High Available solution, along with a feature called ‘vMotion’.
That brought me over to talk about Failover Cluster, CSV and Live Migration. Everything you actually need for this is built into the OS – Windows Server 2008 R2 Enterprise/Datacenter.
In addition, I explained the Dynamic Memory feature in Service Pack 1 in detail for them – compared to VMware.
VMware has the so-called ‘memory overcommit technique’ and provide more RAM to VMs than the physical machine actually has.
1) Serve more memory to the VMs than the physical machine has
2) Identify the same memory blocks (by hash) – in multiple VMs.
3) Compress the host memory by storing those blocks only once.
In Hyper-V, instead of compressing the RAM, it allows the VMs to talk with the host (parent partition) through the VMBus (VSP/VMBus/VSC) to demand more memory. You configure the startup RAM that the VM need to be able to boot, and can also set a limit (maximum RAM). Dynamic Memory works in that way that the host take all available memory (without the memory that is exclusively reserved for the host) and shares it with the running VMs. You can even prioritize your VMs, as well as configure the memory buffer – for performance and optimizing.
- What does it cost? he said.
- Nothing. The Dynamic Memory feature is included in Service Pack 1 for Windows Server 2008 R2.
They had some thinking to do.
One final question
- How could we move our existing VMs from VMware to Hyper-V?
- You can use SCVMM 2008 R2 for this. You can even administer your VMware as well as your entire virtual environment with this tool.
So after a walk-through of their infrastructure, we could confirm that they had everything in place for a Hyper-V deployment, connected to their storage with iSCSI.
The contract they currently have with a vendor that provides VMware solutions expires this summer.
I`ll guess they will re-consider this one, and focus on Hyper-V the next months.
Quite honestly, I am surprised that they actually never had considered Hyper-V for their environment. They just needed some guy to share some basic general information.