With shared networked storage in vSphere you can aggregate storage resources to be more flexible when provisioning the resources to virtual machines. One approach to shared storage is an iSCSI storage area network (SAN), to which you connect using either hardware or software adapters.

Without access to shared storage, the virtual machines on a host are limited to the host's physical hard disk to contain the virtual machines' virtual disks. If you have centralized and aggregated storage resources, it releases virtual machines from depending on local storage. Multiple hosts can access datastores on networked storage concurrently.

ESXi supports iSCSI technology that enables a host to use an IP network to access remote storage. iSCSI technology includes software iSCSI adapters and hardware iSCSI adapters.

Software iSCSI adapter

VMware code that is built into the VMkernel. Your host can connect to the iSCSI storage device through standard network adapters. The software iSCSI adapter handles iSCSI processing while communicating with the network adapter. With the software iSCSI adapter, you can use iSCSI technology without specialized hardware.

Hardware iSCSI adapter

Third-party adapter that offloads iSCSI and network processing from your host. A dependent hardware iSCSI adapter depends on vSphere networking and management interfaces provided by VMware. An independent hardware iSCSI adapter implements its own networking and iSCSI configuration and management interfaces.

For information about the storage options available in vSphere, see the vSphere Storage documentation.

To get access to remote iSCSI devices, you must configure iSCSI adapters according to their type. Follow one of two configuration workflows to configure either software iSCSI adapters or hardware iSCSI adapters.