Modifying iSCSI Port Settings

Basic iSCSI port settings can be modified in the Settings tab of the details page for the port.

Do not alter default settings unless you are familiar with the options and very aware of the affect your changes will have on performance. We highly recommend checking with DataCore Technical Support before making any changes to default settings so that performance is not impacted. Changing port settings requires the port to be re-initialized.

Also see:

Assigning Port Roles and Groups

Configuring iSCSI Connections (iSNS settings)

Changing IP Addresses

Changing the IQN of the Port

The default IQN (iSCSI Qualified Name) can be changed, if desired. The name should be unique.

  • The IQN of an iSCSI initiator port cannot be changed if CHAP authentication is set.
  • All letters in the IQN must be entered in lower case.
  • When the IQN of a target port is changed, the port will be re-initialized.
  • After changing the IQN of a target port that is being used to serve virtual disks, you must logout and login the target port again.
  • After changing the IQN of an iSCSI initiator port, you must logout and login all target ports again.
  • The Microsoft iSCSI initiator port IQN is automatically changed by Microsoft iSCSI Initiator software if the DataCore Server is added or removed from a domain. This behavior is expected and documented by Microsoft. Changing the IQN manually using the procedure below will "fix" the IQN and prevent it from being changed automatically in the future.

To change the IQN:

  1. In the port details page, click Edit.
  2. In the IQN box, enter the new IQN and click Done.
  3. A confirmation message will appear. Read the message for additional instructions and click Yes to continue.
  4. If necessary, open the iSCSI Initiator Details page>Remote Ports tab and Logout and login ports as directed on the confirmation message.

Changing the TCP Port Number

The default TCP port is 3260. This port number should be correct for standard environments.

To change the TCP port number:

  1. In the Settings tab of the iSCSI Port Details page, enter the port number in the TCP port box.
  2. Click Apply and then click Yes on the message to re-initialize the port.

Changing the Maximum Outstanding Target Commands

This setting limits the number of SCSI target commands that are active at the same time. The default setting is 256 maximum outstanding target commands; the range is 1 to 8192 outstanding commands. When this setting is changed, the port will be reinitialized and during that time traffic on the port will be suspended.

For iSCSI ports that have the Mirror (MR) role enabled, the minimum value for outstanding target commands is 2048. For more on the MR role, see Port Connections and Paths.

The maximum number of outstanding commands allocated per initiator is determined dynamically by the number of initiators currently logged in at any given time. For instance, using the default setting of 256 outstanding commands, if one initiator is logged in, that initiator could queue up to 256 commands. If two initiators are logged in, each initiator could queue up to 128 commands and so forth.

The maximum number of initiators per target port is 128; this setting cannot be changed.

Providing initiators with adequate outstanding command queues generally allows for more efficient I/O transactions and therefore optimum throughput. In most cases, the default of 256 outstanding commands per port is sufficient, but in some cases a higher setting may further improve performance. For example, a high speed port that will have many initiators logged in and actively doing I/O simultaneously may benefit from an outstanding commands setting greater than 256. However, higher outstanding commands settings will devote more resources to the port, so experimentation to determine the lowest optimum setting for a specific initiator use case is advised. Contact DataCore Technical Support for guidance when changing the default value.

To change the setting:

  1. In the Settings tab of the server port details page, enter the number in the Maximum outstanding target commands box.
  2. Click Apply and then click Yes on the message to reinitialize the port.

Configuring TCP Congestion Settings

In the TCP Congestion Provider for iSCSI, create a new net transport filter to remove the potential five second delay in iSCSI traffic.