When you set up your host to boot from a SAN, your host's boot image is stored on one or more LUNs in the SAN storage system. When the host starts, it boots from the LUN on the SAN rather than from its local disk.

You can use boot from the SAN if you do not want to handle maintenance of local storage or have diskless hardware configurations, such as blade systems.

ESX and ESXi hosts support different methods of booting from the SAN.

Boot from iSCSI SAN support

Type of Host

Independent Hardware iSCSI

Software iSCSI and Dependent Hardware iSCSI

ESX Host

Supported. An iSCSI HBA is required to boot from the SAN.

Not supported.

ESXi Host

Not supported.

Supported. The network adapter must support the iBFT.

Booting your host from a SAN provides numerous benefits.

Cheaper servers. Servers can be more dense and run cooler without internal storage.

Easier server replacement. You can replace servers and have the new server point to the old boot location.

Less wasted space.

Easier backup processes. The system boot images in the SAN can be backed up as part of the overall SAN backup procedures.

Improved management. Creating and managing the operating system image is easier and more efficient.