所有managed domain在创建的时候(xm new)会将其配置信息写入：
/var/lib/xend/domains/UUID/config.sxp
这样，在dom0重启的时候，xend会将/var/lib/xend/domains下的所有虚机自动创建出来。
该文件的示例如下：
(domain
(domid 49)
(vcpus_params ((cap 0) (weight 256)))
(PV_args 3)
(PV_bootloader /usr/bin/pygrub)
(cpus (() () () () () () () ()))
(VCPUs_live 1)
(actions_after_crash restart)
(uuid 6ad57b30-3eca-4043-9327-6a674ab3b079)
(PV_ramdisk )
(name_label vm1)
(VCPUs_at_startup 1)
(HVM_boot_params ())
(platform
((device_model /usr/lib64/xen/bin/qemu-dm) (videoram 4) (localtime 1))
)
(PV_kernel )
(memory_static_min 0)
(HVM_boot_policy )
(VCPUs_max 8)
(memory_static_max 2147483648)
(actions_after_shutdown destroy)
(memory_dynamic_max 1073741824)
(is_a_template False)
(memory_dynamic_min 1073741824)
(target 0)
(PV_bootloader_args -q)
(other_config ())
(auto_power_on False)
(actions_after_reboot restart)
(s3_integrity 1)
(on_crash restart)
(uuid 6ad57b30-3eca-4043-9327-6a674ab3b079)
(bootloader_args -q)
(vcpus 8)
(name vm1)
(on_poweroff destroy)
(on_reboot restart)
(cpus (() () () () () () () ()))
(bootloader /usr/bin/pygrub)
(maxmem 2048)
(memory 1024)
(shadow_memory 0)
(vcpu_avail '1')
(features )
(on_xend_start ignore)
(on_xend_stop ignore)
(start_time 1319736949.93)
(image
(linux
(kernel )
(args 3)
(videoram 4)
(localtime 1)
(device_model /usr/lib64/xen/bin/qemu-dm)
(notes
(FEATURES
'writable_page_tables|writable_descriptor_tables|auto_translated_physmap|supervisor_mode_kernel'
)
(VIRT_BASE 18446744071562067968)
(GUEST_VERSION 2.6)
(PADDR_OFFSET 0)
(GUEST_OS linux)
(HYPERCALL_PAGE 18446744071564185600)
(LOADER generic)
(SUSPEND_CANCEL 1)
(ENTRY 18446744071564165120)
(XEN_VERSION xen-3.0)
)
)
)
(status 1)
(state ------)
(store_mfn 2263340)
(console_mfn 2263339)
(device
(vif
(bridge eth0)
(mac 00:16:3e:01:6c:cb)
(script /etc/xen/scripts/vif-bridge)
(uuid 8c4ea842-8e20-ab38-531d-9e7c7cbac2b9)
(backend 0)
)
)
(device
(vbd
(protocol x86_64-abi)
(uuid ebac4ba7-2fb4-77e9-d7cd-3b9ce19b1dd5)
(bootable 1)
(dev sda2:disk)
(uname phy:virtualvg2/linux_56_AD00001_2011_10_28_01_34_58)
(mode w)
(backend 0)
(bootable 1)
(VDI )
)
)
(device
(vbd
(protocol x86_64-abi)
(uuid 1387e92c-54ec-45f3-615d-085346f8aed2)
(bootable 0)
(dev sda1:disk)
(uname phy:virtualvg2/linux_56_AD00001_2011_10_28_01_34_58_swap)
(mode w)
(backend 0)
(bootable 0)
(VDI )
)
)
(device (vkbd (backend 0)))
(device
(vfb
(uuid ea025155-9cb1-25b0-e4e0-473fd0f16644)
(vnclisten 0.0.0.0)
(vnc 1)
(vncdisplay 56)
(xauthority /root/.Xauthority)
)
)
)
其中，与xend相关的配置为：默认都是ignore，这样当xend重启的时候，不影响虚机的运行状态
(on_xend_start ignore)
(on_xend_stop ignore)
当然，可以配置虚机与xend同步起停：
(on_xend_start start)
(on_xend_stop shutdown)
所有unmanaged domain在创建的时候(xm create)不会将其配置文件写入上述目录的配置文件中，所有当dom0重启的时候，xend不会自动创建这些虚机。
无论managed domain还是unmanaged domain，在启动的时候都会将其配置写入到xenstore中，在停止的时候从xenstore中删除虚机信息。即xenstore中存放的是所有运行状态（确切的说是除了halt之外）虚机的配置以及前后端设备信息。
