377 Chapter 23: Introduction to Virtualization N File options If you select the checkbox Allocate All Disk Space Now, VMware will create a virtual hard disk file that is the size you selected. Otherwise, VMware will automatically expand the virtual hard disk file’s size as the space is used. The trade-off is that if you choose to allocate the space immediately, the virtual hard disk may consume much more space on the host system’s hard disk than it is actually using. On the other hand, if the space is allocated immediately, then the performance of creating files or writing new blocks to the disk will be much faster, because the space is already allocated. I recommend leaving this checkbox unchecked, but choosing a size that is comfortably larger than you think you need. This way, you efficiently use actual hard disk space, and the automatic expansion process is generally not a huge price to pay for most uses. N Independent disk mode This option allows you to configure a virtual hard disk as independent of any snapshots you make of the virtual machine. Note that you can have multiple virtual hard disks in each virtual machine, and for some applications, you may want the one or more of the virtual hard disks to not be part of the VMware snapshot process. Generally, you will leave this option unselected. Figure 23-8. Setting virtual hard disk properties 378 Networking: A Beginner’s Guide N Virtual device node This setting lets you choose whether VMware will emulate a SCSI or IDE controller for the virtual hard disk you are creating, and which virtualized controller interface number will be used. Realize that the type of hard disk interface used on the host computer does not matter here; VMware can run a virtual SCSI hard disk on a host computer that has only IDE drives or vice versa. For this setting, VMware will propose a virtual disk interface type based on the guest operating system you chose, and you should generally accept the default choice. N Write caching You can set the virtual hard disk to optimize write caching to optimize for data safety or for performance. In a production environment, where the data stored on the virtual machine is important, you should choose Safety. If you’re just experimenting with an operating system and wouldn’t mind if you lost the files stored on it, you can choose Performance. 8. On the Network Adapter page, shown in Figure 23-9, you can choose to create a virtual network adapter for the virtual machine. In most cases, you will need to do this. Click Create a Network Adapter. Figure 23-9. Choosing whether or not to add a network adapter 379 Chapter 23: Introduction to Virtualization 9. On the Properties page for the network adapter, shown in Figure 23-10, you can choose to create three types of network adapters. Select from the following choices, and then click Next. N Bridged This is the default choice and is best for most applications. A bridged virtual network adapter makes use of the host computer’s network adapter, but it obtains its own IP address from the appropriate DHCP server, or it can have an IP address manually assigned to it. The main thing to keep in mind is that if you run many virtual machines simultaneously, each one with a bridged virtual network adapter will use one of the available IP addresses on your network. N Network Address Translation (NAT) When you choose a NAT virtual network adapter, the virtual machine makes use of the IP and MAC addresses of the host computer when it communicates on the network. If you are running various servers as virtual machines, a NAT configuration can be difficult to set up, as you would need to configure port forwarding so that the packets are properly routed to the appropriate virtual machine. Figure 23-10. Setting network adapter properties 380 Networking: A Beginner’s Guide For instance, if you have a web server running in a virtual machine that is using a NAT virtual network interface, you would need to configure the host operating system to forward incoming port 80 (and maybe port 443) packets to that virtual machine. If the virtual machine is running only client-type systems, however, then NAT would help conserve IP addresses on the local network. N HostOnly Choosing HostOnly creates a virtual network on the host computer. Virtual machines that use this type of virtual network adapter can communicate over the network, but only to other running virtual machines on the host computer or to the host computer itself. 10. On the CD/DVD Drive page, shown in Figure 23-11, choose how to access the CD/DVD drive. VMware Server can either share access to the host computer’s CD/DVD drive or it can emulate a CD or DVD drive by connecting to an image file (ISO) stored on the host computer, within the VMware datastore. If the guest operating system download already exists on the host computer as an image file, then choosing this option is very convenient, and means you don’t need Figure 23-11. Setting CD/DVD drive access 381 Chapter 23: Introduction to Virtualization to burn the image file to a piece of optical media. If you are installing a guest operating system that you have on a CD or DVD, then you should create a new virtual CD or DVD drive by choosing Use a Physical Disk. For this example, since you’re probably installing Ubuntu Linux from a downloaded image file, you should choose Use an ISO Image. Once Ubuntu is fully installed, you can change this to give the virtual machine access to the host computer’s CD or DVD drives, if you wish. 11. When you choose Use an ISO Image, you see the Properties page for the CD/DVD drive, as shown in Figure 23-12. Click Browse, and select the ISO file that you placed in the VMware datastore. Make sure that the Connect at Power On option is selected, so that the new virtual machine will be able to boot from the image file, which it will need to do to install the guest operating system. Click Next to continue. Figure 23-12. Setting the CD/DVD drive properties . hard disk as independent of any snapshots you make of the virtual machine. Note that you can have multiple virtual hard disks in each virtual machine, and for some applications, you may want the. Otherwise, VMware will automatically expand the virtual hard disk file’s size as the space is used. The trade-off is that if you choose to allocate the space immediately, the virtual hard disk may consume. with a bridged virtual network adapter will use one of the available IP addresses on your network. N Network Address Translation (NAT) When you choose a NAT virtual network adapter, the virtual