Establishing iSCSI Adapters and SAN Storage with ESXi
Setting up iSCSI Adapters and Storage needs certain level of requirements that must be met before an ESXi can work properly, foremost is to of course follow its basic needs and then follow the best practices in installing and configuring its software or hardware iSCSI (Internet Small Computer Systems Interface) adapters to gain access to the SAN (Storage Area Network).

How to set up basic software iSCSI for VMware vSphere

After setting up the adapters, create a data store on iSCSI storage after which an iSCSI initiator should also be set up, configured, and authenticated before ESX/ESXi can find the iSCSI storage, as recommended below;

• Configure networking for the VMkernel in software and dependent hardware iSCSI. In such cases, network configuration verification by utilizing vmkping utility is an utmost necessity. In hardware iSCSI, configure networking characteristics, typically an IP address, default gateway and subnet mask in the host bus adapter (HBA).

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Multiple Network Adapters in iSCSI Configuration
Note: Physical NICs must be on the same subnet as the iSCSI storage system they connect to | Source: https://pubs.vmware.com/
Networking configuration for iSCSI
Figure 2: The table lists the iSCSI adapters (vmhbas) that ESXi supports and indicates whether VMkernel networking configuration is required | Source: https://pubs.vmware.com/
• If needed, change or check the default initiator’s name.

• The address whereabouts of the typical storage systems should be set and must be pingable using the vmkping.

• For CHAP (Challenge-Handshake Authentication Protocol) authentication, it should be enabled on the initiator and on the storage system. After authentication is enabled correctly, apply it to all targets not yet discovered or discoverable targets, however, these are not applicable to targets already discovered. After setting up the discovery address, utilized new discovered exposed targets and utilized it at that very point.

Vsphere 6.5 iscsi best practices, requirements, and restrictions

As you may already know it, VMware’s ESXi is a serviceable, enterprise-class, type 1 hypervisor created and developed by VMware for purposes of deploying and serving essentially all virtual computers. This ESXi type 1 hypervisor is not any of those software application systems that one normally installs in an OS (operating system), but it is an operating system independent hypervisor-based VMkernel operating system interacting with agents running atop it.

iSCSI SAN Requirements

For ESX/ESXi host to completely work with SAN, several requirements should be met as follows;

• Verify that an updated list of SANs (Storage Area Network) storage firmware and hardware integrations are properly supported by ESX/ESXi.

• Configure the systems to have one VMFS (Virtual Machine File System) data store only in each LUN allocations. VMFS-3 accessibility is not needed.

• Except when using diskless servers (booting from a SAN), it is advisable not to configure the SAN LUN diagnostic partition. Otherwise, an appropriately shared diagnostic partition is advisable.

• Use RDMs for access to any raw disk.

• Set the SCSI controller driver in the guest operating system to queue. Otherwise, set the queue depth during system setup for the physical Host Bus Adapter (HBA).

• Increase the value of SCSI TimeoutValue characteristics to allow Windows to tolerate delayed I/O that results from path failover on virtual machines running Microsoft Windows.

SAN Restrictions

Using ESX/ESXi in an iSCSI SAN storage, specific restrictions will apply, to wit;

• The iSCSI - tape connected devices are supported by ESX/ESXi.

• The virtual - machine multi-pathing software cannot be used in an I/O load balancing performing a single physical LUN.

• An ESX/ESXi also do not support multi-pathing when incorporating an independent hardware iSCSI adapter with either software or dependent hardware adapter.

LUN Allocations Setting

It is paramount to the system to set up LUN allocations when putting together an ESX/ESXi system using iSCSI SAN storage, as stated below;

• Storage Provisioning. Ensuring the ESX/ESXi host accept LUNs during startup, set up all iSCSI SAN targets so that the host can gain access to them and use them. Furthermore, configure the host in such a way that it can find or discover all available iSCSI targets.

• VMware DRS Settings and vMotion. When using VMware DRS and vMotion, make sure that LUNs for the virtual machines are set to all ESX/ESXi hosts. This type of configuration contributes substantially to unconstraint freedoms of moving virtual machines.

• Active-active against active-passive arrays. When using a vMotion or a DRS in an active-passive SAN device, all ESX/ESXi systems must have consistent paths to all SAN processors. Failure of doing it can cause track thumping when a vMotion migration takes place. It is necessary to connect the server to the storage system’s active port. This configuration will ensure that LUNs are set up to the ESX/ESXi host.

Independent Hardware Configuration of iSCSI Adapters

This independent hardware configuration of the iSCSI adapter is a specialized adapter by a third-party that gives the ability to gain access to an iSCSI SAN over TCP/IP, where the iSCSI adapter manages all iSCSI network management processing for the ESX/ESXi system.

It involves the following steps;

• Check whether the adapter requires being licensed.

• Install adapter. View vendor installation documentation.
• Verifying whether the adapter is installed correctly. See View Independent Hardware iSCSI Adapters.

• Configuring discovery addresses for iSCSI Initiators.

• Configuring CHAP parameters for iSCSI Adapters.

For the host to be able to have access to iSCSI storage, install first the independent hardware iSCSI adapter and set up discovery address and CHAP parameters for iSCSI Adapters.

Dependent Hardware Configuration of iSCSI Adapters

This third-party, dependent hardware iSCSI Adapters Vmware is contingent on VMware linking, iSCSI configured and manage interfaces produce by VMware. Although the iSCSI adapter is permitted by automatically making it functional, there’s still a need to set up networking for the iSCSI traffic and bind the adapter and a suitable VMkernel iSCSI port. This adapter can be a card, like a Broadcom 5709 NIC, that bestows a standard network adapter together with iSCSI offload functionality on the same port that appears on the lists as iSCSI adapters on storage adapters.

The steps in configuring a dependent hardware iSCSI adapter, are as follows;

• View the list dependent hardware adapters. Checks if licensed are needed.

• Determine the relationship involving the dependent hardware iSCSI adapters and NICs, making sure to record the designation of the corresponding NICs.

• Configuring the iSCSI networks by generating ports for the iSCSI traffic.

• Binding the iSCSI ports to correlate with dependent hardware iSCSI adapters. This is a necessary step no matter whether there are multiple adapters or just one.

• Configuring iSCSI Initiators’ discovery addresses.

• Configuring iSCSI adapters’ CHAP parameters.

Installing and Configuring Software iSCSI Adapter

In a software-based iSCSI adapter, used a standard NICs to connect the host to a remote iSCSI target on the IP network built into the ESX/ESXi facilitating the connection by communicating with the physical NICs through the network stack. The software iSCSI adapter can be viewed on the list of the storage adapters when connecting to a vCenter Server or a host with the vSphere Client. Before using the software iSCSI adapter, the networking must be set up, enable the adapter, and configures the parameters such as the CHAP and the discovery addresses. The configuration workflow includes the following steps;

• Configuring the iSCSI networks by generating ports for iSCSI traffic.

• Enabling the software iSCSI adapter.

• If using multiple NICs is necessary for the software iSCSI multi-pathing, execute port binding by linking all iSCSI ports to the software iSCSI adapter.

• Enable Jumbo Frames for each vSwitch through the vSphere CLI when needed.

• Configuring discovery addresses for iSCSI Initiators.

• Configuring CHAP parameters for iSCSI Adapters.


Therefore, enabling the software iSCSI adapter is necessary so that the host can use it to access iSCSI storage, but before enabling it, set up the networking for iSCSI. Verify that you have an iSCSI device that is running on the same network as your hosts. A software iSCSI adapter is VMware code that is built into the VMkernel.
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