More VMware intricacies

After two weeks' worth of columns we still are obsessing about VMware and for good reason - it is perhaps the coolest operating system utility we have seen for a long time. Last week we concluded with: "There are interesting options to disk access but they'll have to wait until next week." Next week is here and now . . .

Under VMware Workstation, guest operating systems can directly access the host operating system's hard disk. This is only for the experienced user, as direct host disk access is not constrained in any way, and wiping out the host disk is entirely possible. If you want access to the host disk subsystem you would be better off going with Server Message Block shares.

One of the cool things about guest operating systems under VMware Workstation is you can take a snapshot of the virtual machine. A snapshot captures the contents of a virtual machine's memory along with its settings and the state of all the disks associated with the virtual machine, but you can have only one snapshot per virtual machine. When you save a snapshot, it replaces the current one.

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After two weeks' worth of columns we still are obsessing about VMware and for good reason - it is perhaps the coolest operating system utility we have seen for a long time. Last week we concluded with: "There are interesting options to disk access but they'll have to wait until next week." Next week is here and now . . .

Under VMware Workstation, guest operating systems can directly access the host operating system's hard disk. This is only for the experienced user, as direct host disk access is not constrained in any way, and wiping out the host disk is entirely possible. If you want access to the host disk subsystem you would be better off going with Server Message Block shares.

One of the cool things about guest operating systems under VMware Workstation is you can take a snapshot of the virtual machine. A snapshot captures the contents of a virtual machine's memory along with its settings and the state of all the disks associated with the virtual machine, but you can have only one snapshot per virtual machine. When you save a snapshot, it replaces the current one.

This is useful because if something goes horribly wrong with a virtual machine - say, an application runs amok - you can revert to the last snapshot and the virtual machine will be reset to the state it was in when the snapshot was taken.

Snapshots can be locked to prevent accidental overwriting. You can control the handling of the virtual machine power-off process by specifying that the snapshot shouldn't be modified, that the last snapshot should be restored automatically, that the snapshot should be updated automatically or that the user should be asked what to do.

You also can create a virtual machine that always starts quickly in a known state by suspending the virtual machine when it is in a desired state and taking a snapshot. You then configure the power-off action to revert to that snapshot so every time you "power on" the machine it will be in that saved state.

We installed VMware Workstation under Red Hat Linux 9. For our first virtual machine we set up Windows XP Professional. We put a bootable DOS disk in the physical floppy drive and the Windows installation disk in the CD-ROM drive and powered up the virtual machine. It worked like any other XP installation.

In the first part of this series on VMware we mentioned support for floppies and CD-ROM drives. What is particularly interesting is that these can be physical or virtual devices, and a virtual CD can be a VMware file or an ISO image file (this is a file that contains the complete image of a CD created by copying an entire disk).

Where this feature becomes particularly useful is that you can boot from a physical or a virtual CD-ROM drive by simply setting up the VMware Workstation's virtual Phoenix BIOS appropriately. We could have performed our Windows installation without the floppy boot.

We downloaded an interesting Linux variant called Knoppix that we thought would be interesting to run as a guest under VMware. Knoppix is distinguished by it's an extensive GNU/Linux distribution that boots and runs completely from CD.