We've had problems with it before (migration errors mainly), but it's still miles better than the backup-restore you are forced to use with LXC guests, causing several hours of downtime for large guests.
Consider yourself lucky... Unfortunately, we have many guests where the overhead caused by KVM would make them unusable.
Some of our MySQL guests simply stopped working under KVM (slowed down to a crawl) under high load, while the same workload under OpenVZ gives us 50% higher transactions per second, and much more graceful slowdown under extreme loads. We really need containers, unfortunately LXC is not there yet, so we are forced to stay with OpenVZ for the time being.
Being not alone makes me happy, but as always not a solution to "our" problems.
what can be done ? what is the solution ? I don't want to get rid of openvz, but I also want to use Proxmox 4.x.
I can not find any other alternatives to this beautiful Proxmox we have...
I have to agree these are all issues for the current state of Proxmox and that the OpenVZ ecosystem was "better" as far as we are concerned. As for the other posters comment that live migration of OpenVZ containers never worked properly that is complete garbage. We moved around 1000's of these from one device to another and it worked great. The need for downtime with LXC is terrible, yes it is minimal but downtime is downtime!
That is %100 true for me also..