System information

Using Boot from SAN with ESX
Systems 5
This section discusses the benefits of boot from SAN and describes the tasks you need to perform to have the
ESX boot image stored on a SAN LUN.
NOTE Skip this information if you do not plan to have your ESX host boot from a SAN.
This chapter includes the following topics:
n
“Boot from SAN Overview,” on page 43
n
“Getting Ready for Boot from SAN,” on page 44
n
“Setting Up the QLogic FC HBA for Boot from SAN,” on page 46
n
“Setting Up the Emulex FC HBA for Boot from SAN,” on page 48
Boot from SAN Overview
Before you consider how to set up your system for boot from SAN, decide whether it makes sense for your
environment.
Use boot from SAN in the following circumstances:
n
If you do not want to handle maintenance of local storage.
n
If you need easy cloning of service consoles.
n
In diskless hardware configurations, such as on some blade systems.
You should not use boot from SAN if you expect I/O contention to occur between the service console and
VMkernel.
NOTE With ESX Server 2.5, you could not use boot from SAN together with RDM. With ESX 3.x or later, this
restriction is removed.
How Boot from a SAN Works
When you set up your host to boot from a SAN, the boot image is not stored on the ESX host’s local disk, but
instead is stored on a SAN LUN. The host is informed about the boot image location. When the host is started,
it boots from the LUNs on the SAN array.
On a system set up to boot from a SAN:
n
The HBA BIOS must designate the FC card as the boot controller.
n
The FC card must be configured to initiate a primitive connection to the target boot LUN.
VMware, Inc.
43