Listing and Setting iSCSI Parameters

You can list and set iSCSI parameters for software iSCSI and for dependent hardware iSCSI with ESXCLI or with vicfg-iscsi.

Listing and Setting iSCSI Parameters with ESXCLI

You can retrieve and set iSCSI parameters by running one of the following commands.

Adapter-level parameters	esxcli iscsi adapter param set --adapter=<vmhba> --key=<key> --value=<value>
Target-level parameters	esxcli iscsi adapter target portal param set --adapter=<vmhba> --key=<key> --value=<value> --address=<address> --name=<iqn.name>
Discovery-level parameters	esxcli iscsi adapter discovery sendtarget param set --adapter=<vmhba> --key=<key> --value=<value> --address=<address>

Settable iSCSI Parameters lists all settable parameters. These parameters are also described in the IETF rfc 3720. You can run esxcli iscsi adapter param get to determine whether a parameter is settable or not.

The parameters in Settable iSCSI Parameters apply to software iSCSI and dependent hardware iSCSI.

Settable iSCSI Parameters 

Parameter	Description
DataDigestType	Increases data integrity. When data digest is enabled, the system performs a checksum over each PDUs 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. Valid values are digestProhibited, digestDiscouraged, digestPreferred, or digestRequired.
HeaderDigest	Increases data integrity. When header digest is enabled, the system performs a checksum over the header part of each iSCSI Protocol Data Unit (PDU) and verifies using the CRC32C algorithm.
MaxOutstandingR2T	Max Outstanding R2T defines the Ready to Transfer (R2T) PDUs that can be in transition before an acknowledgement PDU is received.
FirstBurstLength	Maximum amount of unsolicited data an iSCSI initiator can send to the target during the execution of a single SCSI command, in bytes.
MaxBurstLength	Maximum SCSI data payload in a Data-In or a solicited Data-Out iSCSI sequence, in bytes.
MaxRecvDataSegLen	Maximum data segment length, in bytes, that can be received in an iSCSI PDU.
NoopOutInterval	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. Supported only at the initiator level.
NoopOutTimeout	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 NoopTimeout limit is exceeded, the initiator terminates the current session and starts a new one. Supported only at the initiator level.
RecoveryTimeout	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.
DelayedAck	Allows systems to delay acknowledgment of received data packets.

You can use the following ESXCLI commands to list parameter options.

■	Run esxcli iscsi adapter param get to list parameter options for the iSCSI adapter.

■	Run esxcli iscsi adapter discovery sendtarget param get or esxcli iscsi adapter target portal param set to retrieve information about iSCSI parameters and whether they are settable.

■	Run esxcli iscsi adapter discovery sendtarget param get or esxcli iscsi adapter target portal param set to set iSCSI parameter options.

If special characters are in the <name>=<value> sequence, for example, if you add a space, you must surround the sequence with double quotes (“<name> = <value>”).

Returning Parameters to Default Inheritance

The values of iSCSI parameters associated with a dynamic discovery address or a static discovery target are inherited from the corresponding settings of the parent. For the dynamic discovery address, the parent is the adapter. For the static target, the parent is the adapter or discovery address.

■	If you use the vSphere Web Client to modify authentication settings, you deselect the Inherit from Parent check box before you can make a change to the discovery address or discovery target.

■	If you use esxcli iscsi, the value you set overrides the inherited value.

Inheritance is relevant only if you want to return a dynamic discovery address or a static discovery target to its inherited value. In that case, use the following command, which requires the - -name option for static discovery addresses, but not for dynamic discovery targets.

■	Dynamic target: esxcli iscsi adapter discovery sendtarget param set

■	Static target: esxcli iscsi adapter target portal param set

Listing and Setting iSCSI Parameters with vicfg-iscsi

You can list and set iSCSI parameters by running vicfg-iscsi -W. Settable iSCSI Parameters lists all settable parameters. These parameters are also described in the IETF rfc 3720. You can also run vicfg-iscsi - -parameter - -list - -details to determine whether a parameter is settable or not.

The parameters in Settable iSCSI Parameters apply to software iSCSI and dependent hardware iSCSI.

Settable iSCSI Parameters 

Parameter	Description
DataDigestType	Increases data integrity. When data digest is enabled, the system performs a checksum over each PDUs 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. Valid values are digestProhibited, digestDiscouraged, digestPreferred, or digestRequired.
HeaderDigest	Increases data integrity. When header digest is enabled, the system performs a checksum over the header part of each iSCSI Protocol Data Unit (PDU) and verifies using the CRC32C algorithm.
MaxOutstandingR2T	Max Outstanding R2T defines the Ready to Transfer (R2T) PDUs that can be in transition before an acknowledgement PDU is received.
FirstBurstLength	Maximum amount of unsolicited data an iSCSI initiator can send to the target during the execution of a single SCSI command, in bytes.
MaxBurstLength	Maximum SCSI data payload in a Data-In or a solicited Data-Out iSCSI sequence, in bytes.
MaxRecvDataSegLen	Maximum data segment length, in bytes, that can be received in an iSCSI PDU.
NoopOutInterval	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. Supported only at the initiator level.
NoopOutTimeout	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 NoopTimeout limit is exceeded, the initiator terminates the current session and starts a new one. Supported only at the initiator level.
RecoveryTimeout	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.
DelayedAck	Allows systems to delay acknowledgment of received data packets.

You can use the following vicfg-iscsi options to list parameter options. Specify one of the options listed in Connection Options for vCLI Host Management Commands in place of <conn_options>.

■	Run vicfg-iscsi -W -l to list parameter options for the HBA.

vicfg-iscsi <conn_options> -W -l

[-i <stor_ip_addr|stor_hostname> [:<portnum>] [-n <iscsi_name>]] <adapter_name>

 

vicfg-iscsi <conn_options> - -parameter - -list

[- -ip <stor_ip_addr|stor_hostname> [:<portnum>] [- -name <iscsi_name>]] <adapter_name>

The target (-i) and name (-n) option determine what the command applies to.

Option	Result
-i and -n	Command applies to static targets.
Only -i	Command applies to the discovery address.
Neither -i nor -n	Command applies to per-adapter parameters.

■	Run vicfg-iscsi -W -l -k to list iSCSI parameters and whether they are settable.

vicfg-iscsi <conn_options> -W -l -k

[-i <stor_ip_addr|stor_hostname>[:<port_num>] [-n <iscsi_name>]] <adapter_name>

 

vicfg-iscsi <conn_options> - -parameter - -list - -detail

[- -ip <stor_ip_addr|stor_hostname>[:<port_num>][- -name <iscsi_name>]] <adapter_name>

■	Run vicfg-iscsi -W -j to set iSCSI parameter options.

vicfg-iscsi <conn_options> -W -j <name>=<value>

-i <stor_ip_addr|stor_hostname>[:port_num>][-n <iscsi_name>]] <adapter_name>

 

vicfg-iscsi <conn_options> - -parameter - -set <name>=<value>

--ip <stor_ip_addr|stor_hostname>[:port_num>][--name <iscsi_name>]] <adapter_name>

The target (-i) and name (-n) option determine what the command applies to.

Option	Result
-i and -n	Command applies to per-target CHAP for static targets.
Only -i	Command applies to the discovery address.
Neither -i nor -n	Command applies to per-adapter CHAP.

If special characters are in the <name>=<value> sequence, for example, if you add a space, you must surround the sequence with double quotes (“<name> = <value>”).

Returning Parameters to Default Inheritance

The values of iSCSI parameters associated with a dynamic discovery address or a static discovery target are inherited from the corresponding settings of the parent. For the dynamic discovery address, the parent is the adapter. For the static target, the parent is the adapter or discovery address.

■	If you use the vSphere Web Client to modify authentication settings, you deselect the Inherit from Parent check box before you can make a change to the discovery address or discovery target.

■	If you use vicfg-iscsi, the value you set overrides the inherited value.

Inheritance is relevant only if you want to return a dynamic discovery address or a static discovery target to its inherited value. In that case, use the - -reset <param_name> option, which requires the - -name option for static discovery addresses, but not for dynamic discovery targets.

vicfg-iscsi <conn_options> - -parameter - -reset <param_name>

- -ip <stor_ip_addr | stor_hostname>[:port_num>] <adapter_name>

vicfg-iscsi <conn_options> -W - o <param_name>

-i <stor_ip_addr|stor_hostname>[:port_num>] <adapter_name>