When you prepare your iSCSI SAN storage system to work with ESX/ESXi, you need to follow specific general requirements that apply to all storage systems.

For all storage systems, the following general requirements exist:

LUNs must be presented to each HBA of each host with the same LUN ID number. If different numbers are used, the ESX/ESXi hosts do not recognize different paths to the same LUN. Because instructions on how to configure identical SAN LUN IDs are vendor-specific, consult your storage documentation for more information.

Unless specified for individual storage systems discussed in this chapter, set the host type for LUNs presented to ESX/ESXi to Linux or Linux Cluster, if applicable to your storage system. The method ESX/ESXi uses to access the storage system is most compatible with Linux access, however, this can vary depending on the storage system you are using.

If you are using vMotion, DRS, or HA, make sure that source and target hosts for virtual machines can see the same LUNs with identical LUN IDs. SAN administrators might find it counterintuitive to have multiple hosts see the same LUNs because they might be concerned about data corruption. However, VMFS prevents multiple virtual machines from writing to the same file at the same time, so provisioning the LUNs to all required ESX/ESXi system is appropriate.

If you do not have CHAP authentication set up on the LUNs that are being accessed, you must also disable CHAP on the ESX/ESXi host. Otherwise, authentication of the storage system fails, although the LUNs have no CHAP requirement.