There were two impressions to be strict :) Many salesmen and IT specialists convince to buy VMware ESXi5. ESXi is “bare metal hypervisor”computer virtualisation product made by VMware company which was acquired by EMC some time ago. It doesn’t require operating system to be installed because it acts like OS and hypervisor merged together.

So my first time. Somebody said that if I had not free server machine I could install ESXi on common hardware and test it. OK. I thought it is not harm to take older, strong computer. ESXi installation was easy but at the end it appeared that there were no drivers to quite popular hardware so I gave up. There is no way to use it without brand server

I thought that I should choose Linux KVM technology to replace old Xen ( how Amazon can bear Xen ??? ). First it is free. Second in the case of hardware failure I could migrate VMs to some good and cheap common hardware (as in the past). It was hardly possible to be done this way with ESXi.

Second impression. I had access to new server machine so reconsidered to give ESXi second chance. Instalation seemed to be a breeze but when I wanted to install first virtual machine it turned out that I needed MS Windows machine and I had to download 500mb package and install it ! It was quite annoying. After I had managed to get console I installed some VMs. I got a few J# exceptions from management console during first ours of using it. One thing more seemed interesting to me. I read that VMware was based on Linux kernel in earlier versions. I connected to ESXi via ssh and started to explore internal filesystem. It appeared to be like any other UNIX system and many VMware components were taken from Open Source. And my favourite python interpreter was there !

I think VMware ESXi has many drawbacks as:

• price – sales of VMware dropped lately
• architecture: console separated from hypervisor – I consider it error. There are web interfaces and they can be fast and slim.I think some kind of interface shoud be integrated into product for the sake of ease, safety and management.
• it is proprietary – virtualization is basic component of future computer systems and it shoud remain free and open

There is one more fact: VMware ESXi has milions of tickets/bugs on their website.

ESXi is not Holy Grail of virtualization. It has its disadvantages and advantages. Linux KVM or other Open Source virtualization technologies have too. One needs quite much time to learn any technology to be master of it. Even if it is salesman’s shiny VMware.
I have chosen to use KVM and I use it extensively. According to me KVM has great potential and it is still growing. Joining it with cloud software is future of many enterprises. And I find KVM easy to use and especially pairing with existing Linux skills.