When used with a SAN, ESXi can benefit from multiple vSphere features, including Storage vMotion, Distributed Resource Scheduler (DRS), High Availability, and so on.

Using ESXi in conjunction with a SAN is effective for the following tasks:

Storage consolidation and simplification of storage layout

If you are working with multiple hosts, and each host is running multiple virtual machines, the storage on the hosts is no longer sufficient and external storage is required. Choose a SAN for external storage to provide a simpler system architecture along with other benefits.

Maintenance with zero downtime

When performing ESXi host or infrastructure maintenance, use vMotion to migrate virtual machines to other host. If shared storage is on the SAN, you can perform maintenance without interruptions to the users of the virtual machines. Virtual machine working processes continue throughout a migration.

Load balancing

You can add a host to a DRS cluster, and the host's resources become part of the cluster's resources. The distribution and usage of CPU and memory resources for all hosts and virtual machines in the cluster are continuously monitored. DRS compares these metrics to an ideal resource utilization. Ideal utilization takes into account the attributes of the cluster's resource pools and virtual machines, the current demand, and the imbalance target. It then performs (or recommends) virtual machine migrations accordingly.

Disaster recovery

You can use VMware High Availability to configure multiple ESXi hosts as a cluster to provide rapid recovery from outages and cost-effective high availability for applications running in virtual machines.

Simplified array migrations and storage upgrades

When you purchase new storage systems or arrays, use Storage vMotion to perform live automated migration of virtual machine disk files from existing storage to their new destination without interruptions to the users of the virtual machines.