You might need to configure additional parameters for your iSCSI initiators. For example, some iSCSI storage systems require ARP (Address Resolution Protocol) redirection to move iSCSI traffic dynamically from one port to another. In this case, you must activate ARP redirection on your host.

Do not make any changes to the advanced iSCSI settings unless you are working with the VMware support team or otherwise have thorough information about the values to provide for the settings.

Additional Parameters for iSCSI Initiators lists advanced iSCSI parameters that you can configure using the vSphere Client. In addition, you can use the vicfg-iscsi vSphere CLI command to configure some of the advanced parameters. For information, see the VMware vSphere Command-Line Interface Installation and Reference Guide.

Additional Parameters for iSCSI Initiators

Advanced Parameter

Description

Configurable On

Header Digest

Increases data integrity. When header digest is enabled, the system performs a checksum over each iSCSI Protocol Data Unit’s (PDU’s) header part and verifies using the CRC32C algorithm.

Software iSCSI

Data Digest

Increases data integrity. When data digest is enabled, the system performs a checksum over each PDU's data part and verifies using the CRC32C algorithm.

Note

Systems that use Intel Nehalem processors offload the iSCSI digest calculations for software iSCSI, thus reducing the impact on performance.

Software iSCSI

Maximum Outstanding R2T

Defines the R2T (Ready to Transfer) PDUs that can be in transition before an acknowledge PDU is received.

Software iSCSI

First Burst Length

Specifies the maximum amount of unsolicited data an iSCSI initiator can send to the target during the execution of a single SCSI command, in bytes.

Software iSCSI

Maximum Burst Length

Maximum SCSI data payload in a Data-In or a solicited Data-Out iSCSI sequence, in bytes.

Software iSCSI

Maximum Receive Data Segment Length

Maximum data segment length, in bytes, that can be received in an iSCSI PDU.

Software iSCSI

ARP Redirect

Allows storage systems to move iSCSI traffic dynamically from one port to another. ARP is required by storage systems that do array-based failover.

Hardware iSCSI

(Configurable through vSphere CLI)

Delayed ACK

Allows systems to delay acknowledgment of received data packets.

Software iSCSI