Configuring iSCSI software initiator
The software initiator is configured by using SMIT as shown in this procedure.
- Select Devices.
- Select iSCSI.
- Select Configure iSCSI Protocol Device.
- Select Change / Show Characteristics of an iSCSI Protocol Device
- Verify that the Initiator Name value is correct. The Initiator Name value is used by the iSCSI target device during the login operation.Note: A default initiator name is assigned when the software is installed. You can change the initiator name to match local network naming conventions. When you use multiple iSCSI initiator devices, you must assign a unique name for each initiator device.
- The Maximum Targets Allowed field corresponds to the maximum
number of iSCSI target devices that can be configured.
If you reduce this number, you also reduce the amount of network memory pre-allocated for the iSCSI protocol driver during configuration.
Configure the iSCSI discovery method by using the Discovery Policy field
to discover the iSCSI target devices.
The iSCSI initiator software supports the following discovery methods:
- The information about target devices is stored in a configuration file.Note: When the Discovery Policy field is set to
file, the names of the iSCSI target devices are read from the file that you specify in the Discovery file name attribute. When you use multiple instances of the iSCSI software initiator, you must create multiple discovery files if the initiator devices access different iSCSI target devices.
- The information about targets is stored in the Object Data Manager (ODM) objects. When using an iSCSI disk as a boot disk or as part of the rootvg boot, the odm discovery method must be used. See Adding a statically-discovered iSCSI target into ODM.
- The information about targets is stored on an internet Storage Name Service (iSNS) server and automatically retrieved during the iSCSI initiator configuration.
- The information about targets is stored on a Service Location Protocol (SLP) service agent or directory agent and automatically retrieved during the iSCSI initiator configuration.
- Select a value for the isw_err_recov attribute, either delayed_fail or fast_fail. This attribute allows you to set how many times the iSCSI initiator attempts to recover from network errors. The delayed_fail value represents the default behavior that the iSCSI software initiator uses. The delayed_fail value is recommended for environments that have a single iSCSI path to the devices. The fast_fail value reduces various times out values and retry values used by the iSCSI software initiator. This value is the recommended when using multiple paths to the iSCSI device (MPIO), or when the iSCSI devices are utilizing LVM Mirroring. In these situations, if you use the fast_fail value, the AIX operating system switches more quickly to a working path when one path has a network outage.
- Select the required values for the initial_r2t and
immediate_data attributes. By default, the initial_r2t
attribute is set to
yesand the immediate_data attribute is set to
no. You can toggle these values.When you set the intial_r2t attribute to
no, the iSCSI software initiator device can negotiate with the iSCSI target device to not use an initial ready-to-transfer Protocol Data Unit (PDU) while writing data to the iSCSI disk. When you set the immediate_data attribute to
yes, the iSCSI software initiator device can negotiate with the iSCSI target device to send the data immediately to the iSCSI disk. If you select the appropriate values for the intial_r2t and immediate_data attributes, the performance of writing data to the iSCSI disks will improve.
After the software initiator is configured, do the following:
- If the discovery policy is file, edit the /etc/iscsi/targets file to
include the iSCSI targets needed during device configuration.
Each uncommented line in the file represents an iSCSI target. For more information, see targets File in Files Reference.
If the discovery policy is odm, use the mkiscsi command or smit panels to create the target definitions in ODM. For more information, see Adding a statically-discovered iSCSI target into ODM.
If the discovery policy is isns or slp, ensure that the iSNS or SLP server is properly configured and accessible by the iSCSI initiator.
iSCSI device configuration requires that the iSCSI targets can be reached through a properly configured network interface. Although the iSCSI software initiator can work by using a 10/100 Ethernet LAN, it is designed for use with a gigabit Ethernet network that is separate from other network traffic.
- After defining the targets, type the following command:
cfgmgr -l iscsi0
This command reconfigures the software initiator driver. It causes the driver to attempt to communicate with the targets listed in the /etc/iscsi/targets file, and to define a new hdisk for each LUN on the targets that are found. For more information, see the cfgmgr command description.Note: If the appropriate disks are not defined, review the configuration of the initiator, the target, and any iSCSI gateways to ensure correctness, and then rerun the cfgmgr command.
If you want to further configure parameters for iSCSI software initiator devices, use SMIT as follows:
- Select Devices.
- Select Fixed Disk.
hdisk2 Available Other iSCSI Disk Drive
If the iSCSI disk supports command tag queuing and NACA=1 in the control byte, consider changing the queue depth setting of the disk to a larger value. A larger value might help improve device performance. The optimal queue depth setting cannot exceed the actual queue size on the drive. Setting the queue depth to a value larger than the drive's queue size would possibly degrade performance. To determine the drive's queue size, refer the drive documentation.