When you have SAN storage configured with your ESX system, you can place the ESX boot image on one of the LUNs on the SAN. This configuration must meet specific criteria.

To enable your ESX system to boot from a SAN, your environment must meet the requirements listed in Boot from SAN Requirements.

Boot from SAN Requirements

Requirement

Description

ESX system requirements

ESX 3.x or later is recommended. When you use the ESX 3.x system or later, RDMs are supported in conjunction with boot from SAN. For an ESX Server 2.5.x system, RDMs are not supported in conjunction with boot from SAN.

HBA requirements

The HBA BIOS for your HBA FC card must be enabled and correctly configured to access the boot LUN.

The HBA should be plugged into the lowest PCI bus and slot number. This allows the drivers to detect the HBA quickly because the drivers scan the HBAs in ascending PCI bus and slot numbers, regardless of the associated virtual machine HBA number.

Boot LUN considerations

When you boot from an active/passive storage array, the SP whose WWN is specified in the BIOS configuration of the HBA must be active. If that SP is passive, the HBA cannot support the boot process.

To facilitate BIOS configuration, mask each boot LUN so that only its own ESX system can see it. Each ESX system should see its own boot LUN, but not the boot LUN of any other ESX system.

SAN considerations

SAN connections must be through a switched topology if the array is not certified for direct connect topology. If the array is certified for direct connect topology, the SAN connections can be made directly to the array. Boot from SAN is supported for both switched topology and direct connect topology if these topologies for the specific array are certified.

Redundant and nonredundant configurations are supported. In the redundant case, ESX collapses the redundant paths so that only a single path to a LUN is presented to the user.

Hardware- specific considerations

If you are running an IBM eServer BladeCenter and use boot from SAN, you must disable IDE drives on the blades.