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Supersizing Virtual SCSI Drives

Here's how to increase the number of available virtual SCSI drives with VMware Workstation 5.0.

Chris: I've heard that it's possible to add more virtual SCSI disks to VMware Workstation 5.0 virtual machines by editing the VM's configuration file. For various classes that I teach, I like performing demonstrations of how to setup software RAID, but would like to assign more than seven virtual SCSI disks to a VM, which is the limitation through the GUI. Is this possible?
— Andy

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Andy, the rumors that you have heard are correct. VMware Workstation configuration (.vmx) files can be edited in Notepad and thus allow you to extend their capabilities beyond what is possible by configuring VMs using the VMware Workstation user interface. While you are limited to a single virtual SCSI adapter and thus a single SCSI bus with the GUI configuration, you can add a second virtual adapter which can include seven additional drives by manipulating a VM's configuration file.

Here's a procedure for adding four additional SCSI disks to a second virtual SCSI bus:

  1. First create the virtual disk files using the command line tool vmware-vdiskmanager.exe. To do this, open the command prompt and navigate to the VMware Workstation installation folder (default location = "C:\Program Files\VMware\VMware Workstation.") Note that to see the full syntax and examples of using this command, you can run vmware-vdiskmanager.exe /?.
  2. To create the first disk, run the command:

    vmware-vdiskmanager.exe -c -s -a buslogic -t 0

    For example, to create a 2GB virtual disk file named SCSI1-1.vmdk that is stored in the G:\VMs\W2K3 folder, you would run:

    vmware-vdiskmanager.exe -c -s 2Gb -a buslogic -t 0 G:\VMs\W2K3\SCSI1-1.vmdk

  3. Repeat step 2 to create additional disks. For example, to create a disk named SCSI1-2.vmdk, you would run:

    vmware-vdiskmanager.exe -c -s 2Gb -a buslogic -t 0 G:\VMs\W2K3\SCSI1-2.vmdk

  4. Once the disks are created, you will now need to edit the VM's configuration file so that the new disks will be recognized. To open the VM's configuration file, first make sure that the VM is not open in VMware Workstation. Then navigate to the VM's folder using Windows Explorer. Once you locate the VM's configuration file (the one with the .vmx extension), right-click on the file, select Open With, and then click Notepad. (Note that if Notepad is not displayed, you will have to click the Choose Program option and then select Notepad at that point.)
  5. Once the VM's file is opened in Notepad: add the following lines to the beginning of the file:

    scsi1.present = "TRUE"
    scsi1.virtualDev = "buslogic"

    Note that "buslogic" was added since the disks were created for the buslogic virtual SCSI adapter. You could have created virtual disks for an LSILogic SCSI virtual SCSI adapter by specifying "lsilogic" after the -a parameter when the virtual disks were created using vmware-vdiskmanager.exe. The key here is for the references between the virtual disk files and the scsi1.virtualDev reference to point to the same virtual adapter type.
  6. Assuming that you added four virtual SCSI disks, you would add the following lines to the end of the file:

    scsi1:1.present = "TRUE"
    scsi1:1.fileName = "SCSI1-1.vmdk"
    scsi1:2.present = "TRUE"
    scsi1:2.fileName = "SCSI1-2.vmdk"
    scsi1:3.present = "TRUE"
    scsi1:3.fileName = "SCSI1-3.vmdk"
    scsi1:4.present = "TRUE"
    scsi1:4.fileName = "SCSI1-4.vmdk"

At this point, your VM is ready to use the new SCSI disks. Just save the edited .vmx file in Notepad, power up the VM using VMware Workstation, and enjoy!

Getting anything for free always seems to bring out the miser in me. Even if it's just virtual hard disks, I'll take them!

About the Author

Chris Wolf is a Microsoft MVP for Windows --Virtual Machine and is a MCSE, MCT, and CCNA. He's a Senior Analyst for Burton Group who specializes in the areas of virtualization solutions, high availability, storage and enterprise management. Chris is the author of Virtualization: From the Desktop to the Enterprise (Apress), Troubleshooting Microsoft Technologies (Addison Wesley), and a contributor to the Windows Server 2003 Deployment Kit (Microsoft Press).learningstore-20/">Troubleshooting Microsoft Technologies (Addison Wesley) and a contributor to the Windows Server 2003 Deployment Kit (Microsoft Press).

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