Before ESXi can work with iSCSI SAN, you must set up your iSCSI environment. To work properly, your environment must follow specific recommendations. In addition, several restrictions exist when you use ESXi with iSCSI SAN.

iSCSI Storage Recommendations

  • Verify that your ESXi host supports the iSCSI SAN storage hardware and firmware. For an up-to-date list, see VMware Compatibility Guide.
  • To ensure that the host recognizes LUNs at startup time, configure all iSCSI storage targets so that your host can access them and use them. Configure your host so that it can discover all available iSCSI targets.
  • Unless you are using diskless servers, set up a diagnostic partition on local storage. If you have diskless servers that boot from iSCSI SAN, see General Recommendations for Boot from iSCSI SAN for information about diagnostic partitions with iSCSI.
  • Set the SCSI controller driver in the guest operating system to a large enough queue.
  • On virtual machines running Microsoft Windows, increase the value of the SCSI TimeoutValue parameter. With this parameter set up, the Windows VMs can better tolerate delayed I/O resulting from a path failover. For information, see Set Timeout on Windows Guest OS.
  • Configure your environment to have only one VMFS datastore for each LUN.

iSCSI Storage Restrictions

  • ESXi does not support iSCSI-connected tape devices.
  • You cannot use virtual-machine multipathing software to perform I/O load balancing to a single physical LUN.
  • ESXi does not support multipathing when you combine independent hardware adapters with either software or dependent hardware adapters.

Setting Up iSCSI ESXi Environment

The process of preparing your iSCSI environment involves the following steps.

Step Details
1. Set up iSCSI storage For information, see your storage vendor documentation. In addition, follow recommendations in Best Practices for iSCSI Storage.
2. Configure iSCSI/iSER adapters Use an appropriate workflow to configure your adapter:
3. Create a datastore on iSCSI storage Creating Datastores

iSCSI Networking

For certain types of iSCSI adapters, you must configure VMkernel networking.

You can verify the network configuration by using the vmkping utility.

The independent hardware iSCSI adapter does not require VMkernel networking. You can configure network parameters, such as an IP address, subnet mask, and default gateway on the independent hardware iSCSI adapter.

All types of iSCSI adapters support IPv4 and IPv6 protocols.

iSCSI Adapter (vmhba) Description VMkernel Networking Adapter Network Settings
Independent Hardware iSCSI Adapter Third-party adapter that offloads the iSCSI and network processing and management from your host. Not required.

For information, see Edit Network Settings for Hardware iSCSI.

Software iSCSI Adapter Uses standard NICs to connect your host to a remote iSCSI target on the IP network. Required.

For information, see Setting Up Network for iSCSI and iSER.

Dependent Hardware iSCSI Adapter Third-party adapter that depends on VMware networking and iSCSI configuration and management interfaces. Required

For information, see Setting Up Network for iSCSI and iSER.

VMware iSER Adapter Uses an RDMA-capable network adapter to connect your host to a remote iSCSI target. Required

For information, see Setting Up Network for iSCSI and iSER.


Discovery Methods

For all types of iSCSI adapters, you must set the dynamic discovery address or static discovery address. In addition, you must provide a target name of the storage system. For software iSCSI and dependent hardware iSCSI, the address is pingable using vmkping.

See Configure Dynamic or Static Discovery for iSCSI and iSER on ESXi Host.

CHAP Authentication

Enable the CHAP parameter on the initiator and the storage system side. After authentication is enabled, it applies to all targets that are not yet discovered. It does not apply to targets that are already discovered.

See Configuring CHAP Parameters for iSCSI or iSER Storage Adapters.