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 the 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.
| Advanced Parameter | Description | Configurable On |
|---|---|---|
| Header Digest | Increases data integrity. When the header digest parameter is enabled, the system performs a checksum over each header part of the iSCSI Protocol Data Unit (PDU). The system verifies the data using the CRC32C algorithm. | Software iSCSI Dependent Hardware iSCSI |
| Data Digest | Increases data integrity. When the data digest parameter is enabled, the system performs a checksum over each PDU data part. The system verifies the data using the CRC32C algorithm.
Note: Systems that use the Intel Nehalem processors offload the iSCSI digest calculations for software iSCSI. This offload helps to reduce 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 ends 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 iSCSI target sends the message in response to the NOP-Out request. When the no-op timeout limit is exceeded, the initiator ends the current session and starts a new one. | Software iSCSI Dependent Hardware iSCSI |
| ARP Redirect | With this parameter enabled, storage systems can move iSCSI traffic dynamically from one port to another. Storage systems that perform array-based failovers require the ARP parameter. | Software iSCSI Dependent Hardware iSCSI Independent Hardware iSCSI |
| Delayed ACK | With this parameter enabled, storage systems can delay an acknowledgment of received data packets. | Software iSCSI Dependent Hardware iSCSI |
