I just noticed this new KB article that deals about not being able to upgrade ESXi on a Dell box because of the fact that the virtual media is attached:

Upgrade to ESXi 3.5 Update 2.
If you cannot upgrade to ESXi 3.5 Update 2, use the following workaround:

  1. Connect to the DRAC through ILO, as follows:
    1. Open the Media tab.
    2. Open the Configuration tab.
    3. Deselect the Attach virtual media check box.
  2. Boot the ESXi system from the recovery CD.
To use DRAC virtual media to perform the recovery, follow these steps:
  1. Attach the virtual media
  2. Using the virtual media, boot the machine.
  3. When the recovery CD is fully loaded, disconnect the virtual media and proceed with the recovery.

Which reminded of the nice I/O errors this Dell DRAC virtual media produces when attached. So be sure to detach the virtual media before you actually run ESX(i). Same goes for Fujitsu blades by the way, when a virtual media has been present it also produces these nice I/O errors:

Feb 12 09:16:47 esx1 kernel: SCSI device sdc: 2097151 512-byte hdwr sectors (1074 MB)
Feb 12 09:16:47 esx1 kernel: sdc: I/O error: dev 08:20, sector 0
Feb 12 09:16:47 esx1 kernel: I/O error: dev 08:20, sector 0
Feb 12 09:16:47 esx1 kernel: unable to read partition table

Which isn’t as bad as it seems, it’s just not able to read the partition. For Fujitsu blades the only workaround I’ve seen so far was to completely disable USB before booting.