Chapter 5. Virtualization: Configuration Options and Settings / 5.7. Virtual Machine Initial Startup Files
	5.6. Paravirtual Mode and Journaling File Systems		5.8. Sparse Image Files and Disk Space

Virtual Machine Initial Startup Files

During the process of creating a new virtual machine, initial startup settings are written to a file created at /etc/xen/vm/. During the creation process, the virtual machine starts according to settings in this file, but the settings are then transferred and stored in xend for ongoing operations.

	Important
Modifying the initial startup file to create or make changes to a virtual machine is not recommended. The preferred method for changing a virtual machine’s settings is to use Virtual Machine Manager as described in Section 4.3, “Configuring a Virtual Machine by Modifying its xend Settings” or to follow the instructions in Section 5.4, “The Boot Loader Program”.

When a virtual machine’s settings are stored in xend, it is referred to as a xen-managed domain or xen-managed virtual machine. Whenever the xen-managed virtual machine starts, it takes its settings from information stored in the xend database—not from settings in the initial startup file.

Although it is not recommended, you might need to start an existing virtual machine based on settings in the initial startup file. If you do this, any xend settings stored for the virtual machine are overwritten by the startup file settings. Initial startup files are save to /etc/xen/vm/ vm_name . Values must be enclosed in single quotes, such as localtime = '0'.

Table 5.1. Initial Startup File Entries and Descriptions

Entry	Description
disk =	Virtual disks for the virtual machine. For example: disk = [ 'file:/var/lib/xen/images/VM1_SLES10/hda,xvda,w' ] This entry specifies a virtual disk based on a file ( file:) named hda located at /var/lib/xen/images/VM1_SLES10/. It presents itself as the first drive (xvda) and has read/write access (w). Disks can also be based on a block device.
memory =	Virtual memory in Mb.
vcpus =	Number of virtual CPUs.
builder =	Specifies paravirtual mode (Linux) or full virtualization mode (hvm).
name =	Name of the virtual machine.
vif =	Randomly-assigned MAC addresses and bridges assigned to use the virtual machine’s network addresses.
localtime =	Specifies a localtime (0) or UTC (1) time setting.
on_poweroff =	Specifies the action that the virtual machine performs when the operating system is powered off.
on_reboot =	Specifies the action that the virtual machine performs when the operating system reboots.
on_crash =	Specifies the action that the virtual machine performs when the operating system crashes.
extra =	Parameters passed to the kernel.
bootloader =	Location and filename of the domU boot loader.
bootentry =	Location of the kernel and initial ramdisk.
ostype =	Type of operating system.
uuid =	Identification number for a virtual drive.