Modifying iSCSI Initiator and Target Parameters

You can modify parameters on both the iSCSI initiator and the iSCSI target device. However, the only parameters that can be modified on the iSCSI initiator are the following:

iSCSI initiator node name – You can change the initiator node name to a different name. If you change the initiator node name, the targets that were discovered by iSNS might be removed from the initiator's target list, depending on the discovery domain configuration on the iSNS server at the time when the name was changed. For more information, see How to Modify iSCSI Initiator and Target Parameters.
Header digest – NONE, the default value or CRC32.
Data digest – NONE, the default value or CRC32.
Authentication and CHAP secret key – For more information about setting up authentication, see How to Configure CHAP Authentication for Your iSCSI Initiator.
Configured sessions – For more information about configuring multiple sessions, see How to Enable Multiple iSCSI Sessions for a Target.

The iSCSI driver provides default values for the iSCSI initiator and iSCSI target device parameters. If you modify the parameters of the iSCSI initiator, the modified parameters are inherited by the iSCSI target device, unless the iSCSI target device already has different values.

Caution - Ensure that the target software supports the parameter to be modified. Otherwise, you might be unable to log in to the iSCSI target device. See your array documentation for a list of supported parameters.

You can modify the iSCSI parameters only after I/O between the initiator and the target is complete. The iSCSI driver reconnects the session after the changes are made by using the iscsiadm modify command.

Tuning iSCSI Parameters

iSCSI parameters can be tuned to adjust various response or connection time values of the iSCSI initiator. You can tune the iSCSI parameters depending on whether you want to adjust a parameter on the initiator for all targets for which the initiator system is connected or if you want to adjust parameters for a specific target.

Use the following command to change a parameter value of a specific iSCSI target.

iscsiadm modify target-param -T tunable-prop=value target-name

Use the following command to adjust a parameter value for all targets:

iscsiadm modify initiator-node -T tunable-prop=value

The tunable parameters below apply to the active connection, and change the behavior of the iSCSI initiator and the targets that connect to the initiator. The capability to dynamically tune parameters provides flexibility when configuring your iSCSI initiators.

Table 6-1 iSCSI Tunable Parameters

Parameter Name	Description	Valid Values (seconds)	Default Value (seconds)
`recv-login-rsp-timeout`	Session login response time – Specifies how long an iSCSI initiator waits for the response of an iSCSI session login request from a given iSCSI target.	`0` – `3600`	`60`
`conn-login-max`	Maximum connection retry time – Determines the maximum number of times the iSCSI initiator tries to connect to the target, after the iSCSI initiator to target I/O times out, or the connection fails.	`0` – `3600`	`180`
`polling-login-delay`	Login retry time interval – Determines the time interval between each iSCSI session login retry, after the iSCSI initiator to target I/O times out or the connection fails.	`0` – `3600`	`60`

How to Tune iSCSI Parameters

Display all tunable iSCSI parameters.

Display the iSCSI parameter information for all targets.

# iscsiadm list initiator-node
Initiator node name: iqn.1986-03.com.sun:01:e00000000000.4e36d278
Initiator node alias: unknown
        Login Parameters (Default/Configured):
                Header Digest: NONE/-
                Data Digest: NONE/-
                Max Connections: 65535/-
        Authentication Type: NONE
        RADIUS Server: NONE
        RADIUS Access: disabled
        Tunable Parameters (Default/Configured):
                Session Login Response Time: 60/-
                Maximum Connection Retry Time: 180/-
                Login Retry Time Interval: 60/-
        Configured Sessions: 1

Display the iSCSI parameter information for a specific target.

# iscsiadm list target-param [target-name]

For example:

# iscsiadm list target-param -v iqn.1986-03.com.sun:02:47ac0
506-cd48-67f5-fc0d-ab7544d37538
Target: iqn.1986-03.com.sun:02:47ac0506-cd48-67f5-fc0d-ab7544d37538
        Alias: -
        Bi-directional Authentication: disabled
        Authentication Type: NONE
        Login Parameters (Default/Configured):
                Data Sequence In Order: yes/-
                Data PDU In Order: yes/-
                Default Time To Retain: 20/-
                Default Time To Wait: 2/-
                Error Recovery Level: 0/-
                First Burst Length: 65536/-
                Immediate Data: yes/-
                Initial Ready To Transfer (R2T): yes/-
                Max Burst Length: 262144/-
                Max Outstanding R2T: 1/-
                Max Receive Data Segment Length: 8192/-
                Max Connections: 65535/-
                Header Digest: NONE/-
                Data Digest: NONE/-
        Tunable Parameters (Default/Configured):
                Session Login Response Time: 60/-
                Maximum Connection Retry Time: 180/-
                Login Retry Time Interval: 60/-
        Configured Sessions: 1

Tune an iSCSI parameter.
For example, to set the maximum connection retry time to 90 seconds for one target:
```
# iscsiadm modify target-param -T conn-login-max=90 iqn.1986-03.com.sun:
02:47ac0506-cd48-67f5-fc0d-ab7544d37538
```
For example, to set the maximum connection retry time to 90 seconds for all targets:
```
# iscsiadm modify initiator-node -T conn-login-max=90
```

How to Modify iSCSI Initiator and Target Parameters

The first part of this procedure illustrates how modified parameters of the iSCSI initiator are inherited by the iSCSI target device. The second part of this procedure shows how to actually modify parameters on the iSCSI target device.

This optional procedure assumes that you are logged in to the local system where access to an iSCSI target device has already been configured.

Become an administrator.

List the current parameter values for the iSCSI initiator and the target device.

List the current parameter values for the iSCSI initiator.

initiator# iscsiadm list initiator-node
Initiator node name: iqn.1986-03.com.sun:01:0003ba4d233b.425c293c
Initiator node alias: zzr1200
        Login Parameters (Default/Configured):
                Header Digest: NONE/-
                Data Digest: NONE/-
        Authentication Type: NONE
        RADIUS Server: NONE
        RADIUS access: unknown
        Configured Sessions: 1

List the current parameter values for the iSCSI target device.

initiator# iscsiadm list target-param -v iqn.1992-08.com.abcstorage:sn.84186266
Target: iqn.1992-08.com.abcstorage:sn.84186266
        Alias: -
        Bi-directional Authentication: disabled
        Authentication Type: NONE
        Login Parameters (Default/Configured):
                Data Sequence In Order: yes/-
                Data PDU In Order: yes/-
                Default Time To Retain: 20/-
                Default Time To Wait: 2/-
                Error Recovery Level: 0/-
                First Burst Length: 65536/-
                Immediate Data: yes/-
                Initial Ready To Transfer (R2T): yes/-
                Max Burst Length: 262144/-
                Max Outstanding R2T: 1/-
                Max Receive Data Segment Length: 65536/-
                Max Connections: 1/-
                Header Digest: NONE/-
                Data Digest: NONE/-
         Configured Sessions: 1

Note that both header digest and data digest parameters are currently set to NONE for both the iSCSI initiator and the iSCSI target device.

To review the default parameter values for the iSCSI target device, see the iscsiadm list target-param output in Example 6-1.

Modify the parameter of the iSCSI initiator.
For example, set the header digest to CRC32.
```
initiator# iscsiadm modify initiator-node -h CRC32
```
If you change the initiator node name, the targets that were discovered by iSNS might be logged out and removed from the initiator's target list, if the new name does not belong to the same discovery domain as that of the targets. However, if the targets are in use, they are not removed. For example, if a file is open or a file system is mounted on these targets, the targets will not be removed.
You might also see new targets after the name change if these targets and the new initiator node name belong to the same discovery domain.

Verify that the parameter was modified.

Display the updated parameter information for the iSCSI initiator.

initiator# iscsiadm list initiator-node
Initiator node name: iqn.1986-03.com.sun:01:0003ba4d233b.425c293c
Initiator node alias: zzr1200
        Login Parameters (Default/Configured):
                Header Digest: NONE/CRC32
                Data Digest: NONE/-
        Authentication Type: NONE
        RADIUS Server: NONE
        RADIUS access: unknown
        Configured Sessions: 1

Note that the header digest is now set to CRC32.

Display the updated parameter information for the iSCSI target device. For example:

initiator# iscsiadm list target-param -v iqn.1992-08.com.abcstorage:sn.84186266
Target: iqn.1992-08.com.abcstorage:sn.84186266
        Alias: -
        Bi-directional Authentication: disabled
        Authentication Type: NONE
        Login Parameters (Default/Configured):
                Data Sequence In Order: yes/-
                Data PDU In Order: yes/-
                Default Time To Retain: 20/-
                Default Time To Wait: 2/-
                Error Recovery Level: 0/-
                First Burst Length: 65536/-
                Immediate Data: yes/-
                Initial Ready To Transfer (R2T): yes/-
                Max Burst Length: 262144/-
                Max Outstanding R2T: 1/-
                Max Receive Data Segment Length: 65536/-
                Max Connections: 1/-
                Header Digest: CRC32/-
                Data Digest: NONE/-
        Configured Sessions: 1

Note that the header digest is now set to CRC32.

Verify that the iSCSI initiator has reconnected to the iSCSI target.

initiator# iscsiadm list target -v iqn.1992-08.com.abcstorage:sn.84186266
Target: iqn.1992-08.com.abcstorage:sn.84186266
        TPGT: 2
        ISID: 4000002a0000
        Connections: 1
                CID: 0
                  IP address (Local): nnn.nn.nn.nnn:64369
                  IP address (Peer): nnn.nn.nn.nnn:3260
                  Discovery Method: SendTargets
                  Login Parameters (Negotiated):
                        .
                        .
                        .
                        Header Digest: CRC32
                        Data Digest: NONE

(Optional) Reset an iSCSI initiator parameter or an iSCSI target device parameter.
You can reset a parameter to its default value by using the iscsiadm modify command. Or, you can use the iscsiadm remove command to reset all parameters to their default values.
The iscsiadm modify target-param command changes only the parameters that are specified on the command line.
The following example shows how to reset the header digest to NONE:
```
initiator# iscsiadm modify target-param -h none iqn.1992-08.com.abcstorage:sn...
```
For information about the iscsiadm remove target-param command, see iscsiadm(1M).

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