I've created a group consisting of VMs with hostnames like host01-host20. One of the VMs host05 had a problem and I had to delete it using "nova delete". Now Nova does report that it doesn't exist which means it's not in the DB anymore. When I create a new VM, it picks up the hostname as host21. But i want it to pick the missing hostname instead.

I create VM using this command nova boot --flavor <x> --image <y> --count <z> host

Any idea what's wrong and what is needed to achieve that?