The VMware ESX is one the primary building blocks of the vSphere environment. It can be regarded as the “crown jewels” of VMware’s product portfolio because on its slim shoulders much of the rest of the platform sits. In the community its common to refer to VMware ESX, but you will also occasionally hear people refer to it as the “vSphere Host”. The name change is a curious one, and it might indicate an attempt by VMware to distance itself from its “hypervisor” past, and attempt not to be pidgeon-hold as virtualization vendor only.
The ESX host is installed in most case to a physical server which is packed with CPU/Memory and access to high-speed networking (1/10gps) and storage (local Direct Attached Storage or DAS, Fibre-Channel, NFS, iSCSI). The vSphere Host is what enables the SysAdmin to have virtual machines. It can be installed to either local disk, USB/SD-Cards or boot from over the network with PXE (see the “AutoDeploy” chapter) or using Fibre-Channel SAN volumes or LUNs. VMware ESX owns all the devices of the physical server sitting on Ring0 of a typical processor architecture. VMware ESX has it own internal process (or Worlds as they referred to) but its sole and only task is running virtual machines and nothing else. The VMware ESX kernel is extremely light-weight and present a very small surface attack area from a security perspective. This in marked contrast to general purpose operating systems that have been retro-fitted with a virtualization layer, essentially treating the virtualization process as merely another “role” along side others.
The VMware ESX product does come with its own hardware compatibility list or HCL, as well as number of specific minimum hardware requirements which are significant in homelab environments or you are using “nested ESX”. Nested ESX is where you use one virtualization layer (VMware Workstation on PC, or VMware Fusion on the Mac) to run ESX inside a VM. This is popular method of creating a ‘virtual lab’ environment that does require plenty of free memory and good underlying disk subsystem, in most case SSD. The minimum requirements currently are:
NOTE: This bulleted list is a direct cut and paste from the publically available admin guides on vmware.com
- ESXi will install and run only on servers with 64-bit x86 CPUs.
- To support 64-bit virtual machines, support for hardware virtualization (Intel VT-x or AMD RVI) must be enabled on x64 CPUs.
- ESXi requires a host machine with at least two cores.
- ESXi supports only LAHF and SAHF CPU instructions.
- ESXi requires the NX/XD bit to be enabled for the CPU in the BIOS
- ESXi requires a minimum of 4GB of physical RAM. Provide at least 8GB of RAM to take full advantage of ESXi features and run virtual machines in typical production environments.
- One or more Gigabit or 10Gb Ethernet controllers
- Any combination of one or more of the following controllers:
- Basic SCSI controllers. Adaptec Ultra-160 or Ultra-320, LSI Logic Fusion-MPT, or most NCR/Symbios SCSI. RAID controllers. Dell PERC (Adaptec RAID or LSI MegaRAID), HP Smart Array RAID, or IBM (Adaptec) ServeRAID controllers. SCSI disk or a local, non-network, RAID LUN with unpartitioned space for the virtual machines. For Serial ATA (SATA), a disk connected through supported SAS controllers or supported on-board SATA controllers. SATA disks will be considered remote, not local. These disks will not be used as a scratch partition by default because they are seen as remote
VMware offers a rich array of getting VMware ESX on to the hardware. Of course installation to locally attached, mirrored hard-drives is supported – as is an installation to USB/SD-cards. You will find some blades support a small SD-Card slot to allow for boot from this media. Ever since the early days a boot-from-SAN configuration is supported, and this increasingly easier to manage with the onset of converged blade architectures such as Cisco UCS. Additionally, VMware support “AutoDeploy” this allows for the ESX host to boot across the network using PXE. Ancillary services such as DHCP/TFTP and the AutoDeploy Service are used to provide the boot process across the network. In this model the VMware ESX host is “stateless” with its configuration being provided during each boot process using the “Host Profiles” feature. You should be aware that both AutoDeploy and Host Profiles are licensed technologies and are currently only available to Enterprize+ customers. As such this could limit it applicability to your production environment. Finally, what ever “install” method you adopt (local, media, SAN) VMware ESX does support scripted installation which can massively decrease the deployment time as well as enforcing company standards and settings. These topics are beyond the scope of this article where the focus is on a manual installation to local storage. For other methods please consult the other chapter of the vmWIKI for vSphere.
During the setup process the install media can see any storage that the vSphere Host is configured to access. Care must be taken to not accidentally destroy data on LUNs/Volumes presented to the host. There a number of methods to stop the vSphere Host being able to see remote storage. These include:
- Disconnect Fibre-Channel Cables/Ethernet Cables
- Disable the Fibre-Channel PCI Device from within the server BIOS
- Use Storage Management to Storage to ensure access to remote storage is not possible
The vSphere Host/VMware ESX software downloads as DVD .iso image that can either be mounted directly using your server vendors ILO/DRAC/RAC/BMC board or else burned to a DVD disk, and then used with the DVD player. It’s recommend to use the “Download Manager” option as this support auto-resumme in the event of network outage. It’s also recommend to use a md5sum tool to validate the downloaded .ISO is not corrupted. If your using Linux or Apple Mac these operating systems ship with a “md5” command-line tool. Those SysAdmin using Windows are recommend to use NullRiver Software’s WinMD5sum
Caption: This screen shot shows the main download page at vmware.com. Highlighted in red is the MD5 hash value.
Caption: This screen shot show the Windows WinMD5sum application. The MD5 hash of the download .ISO file matches the one published on VMware’s website.
Installing VMware ESX
Version: vSphere 5.5
1. Attach the DVD to your server – in this example a HP DL385 G1 was used which has an onboard “ILO” Management Card. This is quite an old server, and should see a more modern UI on a contemporary system. In this case the HP ILO’s “Virtual Media” feature was used to mount the VMware ESX DVD .ISO to the physical host, and the host powered on. By default the VMware ESX host installer pauses briefly for 10seconds at this boot menu screen.
2. After this the install will continue to load the files required for installation.
3. Once completed the kernel that makes up VMware ESX (referred to as the VMKernel) is loaded.
4. Once the system load has completed, you will see the welcome screen
5. And the obligatory EULA – pressing [F11] Accepts and Continues this.
6. Next you will need select a disk to hold the VMware ESX software. In this case we have rather foolish allow the physical server to see storage on the FC-SAN this is very dangerous.
7. It is possible to select each disk/volume/LUN and request details with [F1]
8. If a disk is selected which already contains a VMware File System (VMFS) and this is an existing installation – you will have option to either upgrade and keep the VMs; carry out a clean installation but preserve the VMFS file system from the previous installation – or completely re-install and wipe the system.
9. Select your language.
10. Set the password for the “root” user account. The installer does not enforce or warning you about complexity. So very simple passwords such as Password1 will work.
11. If you are working on a very old server or a server who settings have not been correctly configured you will recieve warnings about lack of support for CPU extensions that improve performance or security. In this case the AMD chipset does not support the AMD-V attributes.
12. Finally, you are given one last chance to abort the installation.
13. Then the installer will copy the software to the disk/volume/LUN you selected earlier.
14. At the end of the install pressing [ENTER] will trigger a reboot – be sure to eject or close any mounted .ISO or physical DVD in the server.
15. After the reboot you should be confronted with the VMware ESX “Direct User Console Interface” (DUCI). This allows a number of post-configuration tasks to take place, and also be used as one method of troubleshooting an ESX host if become unresponsive. Notice how by default VMware ESX defaults to using DHCP, and will recieve a DHCP delivered IP address if the service exists on your network.