A /64 in IPv6 is what a single address is for IPv4.
I don't agree on this when talking about connecting servers.
What is a server? It is not unusual to see a 1U rackmount device called a "server" in hosting data centres. These server things have 4 CPU chips each with 4 cores, and 64G of RAM. Each of the 16 cores can run at least 3 average virtual machines giving you 48 vms in the device, and it is common enough to see people running as many as 7 or 8 VMs per core so you could easily have 112 VMs. In addition to the 112 virtual servers, each needing a /128 for every one of their virtual network interfaces, it is common to find people implementing virtual networks with virtual routers and switches, including a virtual DMZ/firewall setup. Clearly it is not unusual to find a so-called server device that actually does require more than a /64 allocation in order to remain aligned with IPv6 architecture and not start subnetting /64 blocks. --Michael Dillon