Citrix has listed the new scalability limits for XenServer 7.5 within the published configuration limits document https://bit.ly/2rcrjZx
- Concurrent VMs per host (Windows or Linux): 1000
- Concurrent protected VMs per host with HA enabled: 500
Disclaimers are:
- The maximum number of VMs/host supported is dependent on VM workload, system load, and certain environmental factors. Citrix reserves the right to determine what specific environmental factors affect the maximum limit at which a system can function. For systems running over 500 VMs, Citrix recommends allocating 8GB RAM and 8 exclusively pinned vCPUs to dom0, and setting the OVS flow-eviction-threshold to 8192.
The maximum amount of logical physical processors supported differs by CPU. Please consult the XenServer Hardware Compatibility List for more details on the maximum amount of logical cores supported per vendor and CPU.
Each plugged VBD or plugged VIF or Windows VM reduces this number by 1