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.

The following table lists advanced iSCSI parameters that you can configure using the vSphere Web Client. In addition, you can use the vSphere CLI commands to configure some of the advanced parameters. For information, see the Getting Started with vSphere Command-Line Interfaces documentation.

Important

Do not make any changes to the advanced iSCSI settings unless you are directed by VMware support or Storage Vendors.

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

Dependent Hardware 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

Dependent Hardware iSCSI

Maximum Outstanding R2T

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

Software iSCSI

Dependent Hardware 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

Dependent Hardware iSCSI

Maximum Burst Length

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

Software iSCSI

Dependent Hardware iSCSI

Maximum Receive Data Segment Length

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

Software iSCSI

Dependent Hardware iSCSI

Session Recovery Timeout

Specifies the amount of time, in seconds, that can lapse while a session recovery is performed. If the timeout exceeds its limit, the iSCSI initiator terminates the session.

Software iSCSI

Dependent Hardware iSCSI

No-Op Interval

Specifies the time interval, in seconds, between NOP-Out requests sent from your iSCSI initiator to an iSCSI target. The NOP-Out requests serve as the ping mechanism to verify that a connection between the iSCSI initiator and the iSCSI target is active.

Software iSCSI

Dependent Hardware iSCSI

No-Op Timeout

Specifies the amount of time, in seconds, that can lapse before your host receives a NOP-In message. The message is sent by the iSCSI target in response to the NOP-Out request. When the no-op timeout limit is exceeded, the initiator terminates the current session and starts a new one.

Software iSCSI

Dependent Hardware 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.

Software iSCSI

Dependent Hardware iSCSI

Independent Hardware iSCSI

Delayed ACK

Allows systems to delay acknowledgment of received data packets.

Software iSCSI

Dependent Hardware iSCSI