How many desktops can a XenDesktop 5.x site support? Tests have been done showing that a site can support 10,000, 20,000 or more desktops. But my question is if it really matters. After a certain number, Citrix always am left to wonder if putting that many desktops in a single site is really a good idea. It all comes down to what level of risk you are willing to take. Let me go through what Daniel Feller means:
- Host Risk: At the base level, we have a hypervisor host (XenServer, Hyper-V or vSphere). Depending on the hardware and user workload, I’ll be running somewhere between 50-100 virtual Windows 7 desktops on each host. If the host has a catastrophic failure, those desktops go offline. Users will try to reconnect and they will be sent to other hosts. This is why we recommend N+1 at a minimum. If you lose one host, you should have at least one extra one to take over. If you lose a host, you can expect most of those users to try to reconnect immediately. Trying to support 50-100 connections is easy.
Pool/Cluster Risk: One level higher than the host is a group of hosts in a pool or cluster. You will probably have around 800 desktops in a pool/cluster if we assume you have 10 hosts in a cluster. What happens if we lose the cluster? Depending on the type of failure, you will have one of the following:
- Connection Failure: If you have a failure where the pool/cluster controller fails, you won’t be able to launch new desktops, but currently active users will be unaware of any issues.
- Pool/Cluster Failure: If you lose an entire pool/cluster, you have to find a place for those 800 desktop users. Again, if you have N+1 fault tolerance, you probably have spare capacity within your entire environment. You also need to make sure your infrastructure can support 800 users trying to connect simultaneously. This still isn’t that big of a connection storm.