KVM Review

I had lots of issue with it.

I have used KVM with centos 7. Unfortunately, I had lots of issue with it. First of all, I wanted all the VMs to share the same network. I had to modify the centos network interface files myself. I had to do it with every single VM. 

At some point it created lots of issue in the module firewalld which also act as the nat to connect the VM with the physical interface. I could read "command failed" for rules of a VM that was already deleted in KVM. 

Then, I had issues with virsh the command line of KVM. Among other things, it exports and imports VM. I wanted to move a Virtual Machines from kvm on centos bare metal server to kvm on debian bare metal server and I discovered that in order to do so, I had to modify the XML configuration inside the VM file. 

I have also been unable to clone VMs meaning they when i tried to run some VMs after cloning, they refused to start. I have also crashed the Centos host. At that point, I have decided to stop and move to my old friend Vmware workstation on Linux. I didn't have to modify any interface files and I could use a "bridge" mode by choosing it in the options so that all my VM were on the same network. Ok, Vmware workstation isn't a bare metal hypervisor but it is reliable. 

By the way, I prefer to spend time on developing stuff than spending my time setting up KVM or learning the commands of virsh to do basic stuff with it. 

On the internet, many geeks pinpoint the performance of KVM. It is true but it is futile issue as compared to issues related to a production environment. 

I am sorry to say that online propaganda made believe that KVM is a mature product that should be considered for production. I think KVM may be good for a lab where the VMs aren't critical.

Now, when I see Web hosting providers who run the Vps on top of KVM, I don't see them the same way. 

This made me aware of the issue related to the Type 1 hypervisor. Since a type 1 is a bare metal type hypervisor, it deals with masquerading (NAT), security, kernel, memory, data IO... Because of that, every module has to extremely stable and bug free. As I said before, I have been able to crash a centos 7 bare metal host (meaning it didn't reboot) without tweaking any packages or renaming any files. Just by doing heavy normal maintenance over Virtual machines. (Deleting, adding, cloning, changing virtual hardware, changing network data, Changing name...). 

On the other hand Vmware workstation is a Type 2 hypervisor meaning that this software is going to interact with the host without really modifying it. I did the same things as with KVM without any crash.

I am a MCSE and i have started "hypervising" with Ms Hyper V which is way better than KVM. As i am writing this, I think about all the good things, people write online about KVM. It makes believe that KVM is as good as Hyper V. However, it is not close to the truth. Hyper V is more stable. Its files are more portable. The migration features are robust. More importantly, it uses hardware better than Linux based KVM.

Which version of this solution are you currently using?

from Centos 7
**Disclosure: I am a real user, and this review is based on my own experience and opinions.
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ITCS user

author avatarit_user202179 (IS Infrastructure Planner with 1,001-5,000 employees)

It gives a real world view of KVM, VMware and Hyper-V.

author avatarFábio Rabelo
Top 5Real User

I am sorry your experience have not been what you expected .
I use KVM in production environment for over 4 years now, with no issues .
What you need is a REAL Linux distro ( Like Debian ) and a good web interface ( I use Proxmox ) .
If you have time, try it .

author avatarit_user239358 (Business process Advisor for RTP at a energy/utilities company with 10,001+ employees)
Real User

Fábio Rabelo, you are right. It looks like many issues were related to Centos 7 & not KVM. I switched to Debian 8.