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theVMguy’s Notable KB articles from the week

by Roger Lund

http://vmguy.com/wordpress/index.php posts his weekly Notable KB articles from the week.



Apparently the VMware support team got back to work full steam ahead this week.  81 articles were new or updated this week.  There are some really good troubleshooting ones this week.  Here’s this week’s selection:

Thanks to the VMguy, and VMware for Content.

A few of the articles that caught my eye.


Converting a virtual disk into a Raw Device Mapping

KB Article

Jan. 12, 2009


VMware ESX


What is the command to convert a virtual disk into a Raw Device Mapping in ESX environment?


A virtual disk can be imported into a raw LUN for use with an RDM using following commands:

  • For virtual compatibility mode use: vmkfstools –i <srcfile> -d rdm:/vmfs/devices/disks/vmhbac:t:l:p /vmfs/volumes/datastore/vmdir/vmname.vmdk

  • For physical compatibility mode use: vmkfstools –i <srcfile> -d rdmp:/vmfs/devices/disks/vmhbac:t:l:p /vmfs/volumes/datastore/vmdir/vmname.vmdk


GHO image files cannot be converted

KB Article

Jan. 09, 2009


VMware Converter


  • Cannot select Symantec Ghost/Norton Ghost image files as source for a virtual to virtual conversion
  • .GHO files cannot be selected as a source


Image files created as .GHO format are not supported by Converter. You must use an image format with the file extension .sv2i.

The following Symantec formats are supported by Converter 3.x:

  • Norton Ghost version 9.0, 10.0, and 12.0 (.sv2i files only)

  • Symantec Backup Exec System Recovery (formerly LiveState Recovery) 6.5 and 7.0

  • LiveState Recovery 3.0 and 6.0

A detailed list of supported formats for VMware Converter 3.x is included in the Converter 3.0.3 User’s Manual.




SCSI and Jumbo Frames configuration on ESX 3.5

KB Article

Jan. 05, 2009


VMware ESX

Product Versions

VMware ESX 3.5.x


  • Large queues are seen while monitoring Jumbo Frames


This article provides information related to setting up an iSCSI environment with Jumbo Frames.


Important Jumbo Frame Information

The following is important information to know when using Jumbo Frames:

  • Any packet larger than 1500 MTU is a Jumbo Frame. ESX 3.5 supports frames up to 9kB (9000 Bytes). They are limited to data networking only (virtual machines and the VMotion network) on ESX 3i/3.5.

  • Jumbo Frames are not supported for NAS and iSCSI traffic at this time.

  • Jumbo Frames must be enabled for each vSwitch or VMkernel interface through the command‐line interface on your ESX Server 3 host.
  • To allow ESX Server 3 to send larger frames out onto the physical network, the network must support Jumbo Frames end to end for Jumbo Frames to be effective.

  • Before enabling jumbo frames, ensure the NIC or LOM supports jumbo frames.
  • VMware supports jumbo frames with the following vendors:

    • Intel (82546, 82571),

    • Broadcom (5708, 5706, 5709),

    • Netxen (NXB-10GXxR,

    • NXB-10GCX4),

    • Neterion (Xframe, Xframe II, Xframe E).

Creating a Jumbo Frames-enabled vSwitch
  1. Log in directly to your ESX Server 3 hostʹs console.
  2. Run the esxcfg-vswitch -m <MTU> <vSwitch> command to set the MTU size for the vSwitch.
    This command sets the MTU for all uplinks on that vSwitch. Set the MTU size to the largest MTU size among all the virtual network adapters connected to the vSwitch.

  3. Run the esxcfg-vswitch -l command to display a list of vSwitches on the host, and check that the configuration of the vSwitch is correct.

Creating a Jumbo Frames-enabled VMkernel interface

To create a Jumbo Frames-enabled VMkernel interface:

  1. Log in directly to your ESX Server 3 host’s console.

  2. Run the esxcfg-vmknic -a -i <ip address> -n <netmask> -m <MTU> <portgroup name> command to create a VMkernel connection with Jumbo Frame

  3. Run the esxcfg-vmknic -l command to display a list of VMkernel interfaces, and check that the configuration of the Jumbo Frame‐enabled interface is correct.
    Note: ESX Server 3 supports a maximum MTU size of 9000.

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