Booting your ESX host from a SAN provides numerous benefits.

The benefits include:

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.