To make a VM automatically start on XenServer boot here you can find how to configure it:
First, look up for the uuid of the server we want to make it auto poweron with
[root@MacXen ~]# xe vm-list|less
Check what is the current configuration
[root@MacXen ~]# xe vm-param-get uuid=4560610b-2f8c-7122-8f95-08880d327228 param-name=other-config vgpu_pci: ; auto_poweron: ; base_template_name: Other install media; mac_seed: 8d934b58-0939-1eb5-7e0f-2c28832c2c63; install-methods: cdrom
Setup the auto_poweron parameter
[root@MacXen ~]# xe vm-param-set uuid=4560610b-2f8c-7122-8f95-08880d327228 other-config:auto_poweron=true
Check again if the auto_poweron is enabled.
[root@MacXen ~]# xe vm-param-get uuid=4560610b-2f8c-7122-8f95-08880d327228 param-name=other-config auto_poweron: true; vgpu_pci: ; base_template_name: Other install media; mac_seed: 8d934b58-0939-1eb5-7e0f-2c28832c2c63; install-methods: cdrom