Tuning iSCSI Parameters

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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 4-1 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
```