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3.3. Preparing a Hypervisor USB Storage Device

The Hypervisor is able to install from USB storage devices and solid state disks. However, the initial boot/install USB device must be a separate device from the installation target. Network booting with PXE and tftp provides the greatest flexibility and scalability. For environments where network restrictions prevent network booting, or for systems without PXE capable network interface cards, a local media installation such as CD-ROM or USB is necessary. Booting from USB storage devices is a useful alternative to booting from CD, for systems without CD-ROM drives.

Note — USB Boot Support

Not all systems support booting from a USB storage device. Ensure that your system's BIOS supports booting from USB storage devices before proceeding.

3.3.1. Making a USB Storage Device into a Hypervisor Boot Device

This section covers making USB storage devices which are able to be used to boot Hypervisors.

3.3.1.1. Using rhevh-iso-to-disk to Create USB Install Media

The rhevh-iso-to-disk command will install a Hypervisor onto a USB storage device. The rhevh-iso-to-disk command is part of the rhev-hypervisor package. Devices created with this command are able to boot the Hypervisors on systems which support booting via USB.
The basic rhevh-iso-to-disk command usage follows this structure: 
# rhevh-iso-to-disk image device
Where the device parameter is the partition name of the USB storage device to install to. The image parameter is a ISO image of the Hypervisor. The default Hypervisor image location is /usr/share/rhev-hypervisor/rhev-hypervisor.iso. The rhevh-iso-to-disk command requires devices to be formatted with the FAT or EXT3 file system.

Note — Partitions and rhevh-iso-to-disk

rhevh-iso-to-disk uses a FAT or EXT3 formatted partition or block device.
USB storage devices are sometimes formatted without a partition table, use /dev/sdb, or similar, as the device name to be used by rhevh-iso-to-disk.
When a USB storage device is formatted with a partition table, use /dev/sdb1, or similar, as the device name to be used by rhevh-iso-to-disk.
  1. Install the rhev-hypervisor package. Refer to Downloading and Installing the RPM Package
  2. Use the rhevh-iso-to-disk command to copy the .iso file to the disk. The --format parameter formats the disk. The --reset-mbr initializes the Master Boot Record (MBR). The example uses a USB storage device named /dev/sdc.
    Example 3.1. Use of rhevh-iso-to-disk
    # rhevh-iso-to-disk --format --reset-mbr /usr/share/rhev-hypervisor/rhev-hypervisor.iso /dev/sdc
Verifying image...
/usr/share/rhev-hypervisor/rhev-hypervisor.iso:   eccc12a0530b9f22e5ba62b848922309
Fragment sums: 8688f5473e9c176a73f7a37499358557e6c397c9ce2dafb5eca5498fb586
Fragment count: 20
Checking: 100.0%

The media check is complete, the result is: PASS.

It is OK to use this media.
Copying live image to USB stick
Updating boot config file
Installing boot loader
syslinux: only 512-byte sectors are supported
USB stick set up as live image!

The USB storage device (/dev/sdc) is ready to boot a Hypervisor.

3.3.1.2. Using dd to Create USB Install Media

The dd command can also be used to install a Hypervisor onto a USB storage device. Media created with the command can boot the Hypervisor on systems which support booting via USB. Red Hat Enterprise Linux provides dd as part of the coreutils package. Versions of dd are also available on a wide variety of Linux and Unix operating systems.
Windows users are able to obtain the dd command through installation of Red Hat Cygwin, a free Linux-like environment for Windows. Refer to Procedure 3.4, “Using dd to Create USB Install Media on Systems Running Windows” for instruction on the installation and use of Red Hat Cygwin to install the Hypervisor to a USB storage device.
The basic dd command usage follows this structure: 
# dd if=image of=device
Where the device parameter is the device name of the USB storage device to install to. The image parameter is a ISO image of the Hypervisor. The default Hypervisor image location is /usr/share/rhev-hypervisor/rhev-hypervisor.iso. The dd command does not make assumptions as to the format of the device as it performs a low-level copy of the raw data in the selected image.
Procedure 3.3. Using dd to Create USB Install Media
  1. Install the rhev-hypervisor package. Refer to Downloading and Installing the RPM Package
  2. Use the dd command to copy the .iso file to the disk. The example uses a USB storage device named /dev/sdc.
    Example 3.2. Use of dd
    # dd if=/usr/share/rhev-hypervisor/rhev-hypervisor.iso of=/dev/sdc
243712+0 records in
243712+0 records out
124780544 bytes (125 MB) copied, 56.3009 s, 2.2 MB/s

    Warning — All Data on the Device Specified Will be Overwritten

    The dd command will overwrite all data on the device specified for the of parameter. Any existing data on the device will be destroyed. Ensure that the correct device is specified and that it contains no valuable data before invocation of the dd command.
  3. Result:
    The USB storage device (/dev/sdc) is ready to boot a Hypervisor.
Procedure 3.4. Using dd to Create USB Install Media on Systems Running Windows
  1. Access http://www.redhat.com/services/custom/cygwin/ and click the Red Hat Cygwin official installation utility link. The rhsetup.exe executable will download.
  2. As the Administrator user run the downloaded rhsetup.exe executable. The Red Hat Cygwin installer will display.
  3. Follow the prompts to complete a standard installation of Red Hat Cygwin. The Coreutils package within the Base package group provides the dd utility. This is automatically selected for installation.
  4. Copy the rhev-hypervisor.iso file downloaded from Red Hat Network to C:\rhev-hypervisor.iso.
  5. As the Administrator user run Red Hat Cygwin from the desktop. A terminal window will appear.

    Note — Run Red Hat Cygwin as Administrator

    On the Windows 7 and Windows Server 2008 platforms it is necessary to right click the Red Hat Cygwin icon and select the Run as Administrator... option to ensure the application runs with the correct permissions.
  6. In the terminal run cat /proc/partitions to see the drives and partitions currently visible to the system.
    Example 3.3. View of Disk Partitions Attached to System
    Administrator@test /
$ cat /proc/partitions
major minor  #blocks  name
    8     0  15728640 sda
    8     1    102400 sda1
    8     2  15624192 sda2

  7. Plug the USB storage device which is to be used as the media for the Hypervisor installation into the system. Re-run the cat /proc/partitions command and compare the output to that of the previous run. A new entry will appear which designates the USB storage device.
    Example 3.4. View of Disk Partitions Attached to System
    Administrator@test /
$ cat /proc/partitions
major minor  #blocks  name
    8     0  15728640 sda
    8     1    102400 sda1
    8     2  15624192 sda2
    8    16    524288 sdb

  8. Use the dd command to copy the rhev-hypervisor.iso file to the disk. The example uses a USB storage device named /dev/sdb. Replace sdb with the correct device name for the USB storage device to be used.
    Example 3.5. Use of dd Command Under Red Hat Cygwin
    Administrator@test /
$ dd if=/cygdrive/c/rhev-hypervisor.iso of=/dev/sdb& pid=$!

    The provided command starts the transfer in the background and saves the process identifier so that it can be used to monitor the progress of the transfer. Refer to the next step for the command used to check the progress of the transfer.

    Warning — All Data on the Device Specified will be Overwritten

    The dd command will overwrite all data on the device specified for the of parameter. Any existing data on the device will be destroyed. Ensure that the correct device is specified and that it contains no valuable data before invocation of the dd command.
  9. Transfer of the ISO file to the USB storage device with the version of dd included with Red Hat Cygwin can take significantly longer than the equivalent on other platforms.
    To check the progress of the transfer in the same terminal window that the process was started in send it the USR1 signal. This can be achieved by issuing the kill in the terminal window as follows: 
    kill -USR1 $pid
  10. When the transfer operation completes the final record counts will be displayed.
    Example 3.6. Result of dd Initiated Copy
    210944+0 records in
210944+0 records out
108003328 bytes (108 MB) copied, 2035.82 s, 53.1 kB/s

[1]+	Done			dd if=/cygdrive/c/rhev-hypervisor.iso of=/dev/sdb

  11. Result:
    The USB storage device (/dev/sdb) is ready to boot a Hypervisor.