Configuring multiple iSCSI software initiator devices

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The internet Small Computer Systems Interface (iSCSI) software creates a device to represent the iSCSI software initiator. By default, the device is named iscsi0. This device has an initiator_name attribute that contains the iSCSI name that is associated with the device.

You can create multiple iSCSI software initiator devices in a single AIX® operating system instance. Having multiple iSCSI software initiator devices provides the following advantages:

  • You can easily create multiple Multipath I/O (MPIO) paths for an iSCSI disk that supports MPIO. Each MPIO path creates its own TCP/IP socket connection, so the iSCSI data traffic is spread across more connections to improve performance by increasing concurrent processing.
  • Multiple iSCSI I/O requests can be separated logically. The disks in the iscsi0 device might be used by an application while the disks in the iscsi1 device might be used by another application. In such cases, separating the I/O requests reduces the chances of I/O request conflicts between applications.
To create an iSCSI software initiator device, run the following command:
mkdev -c driver -s node -t iscsi -d
This command creates an iSCSI software initiator device and prints the name of the device. You can create multiple initiator devices by using the mkdev command. You are suggested not to create or use more than 8 iSCSI initiator devices.

After the device is created, you must assign a unique name to the device. You can use the chdev command to set the initiator_name attribute of the new device. You must also configure the new device to access certain iSCSI target devices similar to the configuration of the iscsi0 device. When you create multiple iSCSI software initiator devices, you can configure the devices to access the same iSCSI target devices or different iSCSI target devices.

If two initiator devices are accessing the same target devices and are using the file discovery policy (that is, if the disc_policy attribute is set to file), the two initiator devices might point to the same file name. If two initiator devices access different target devices, the two initiator devices must point to different file names. If two initiator devices are accessing the same target devices and are using the Object Data Manager (ODM) discovery policy (that is, if the disc_policy attribute is set to odm), the ODM entries for the first initiator device must be duplicated to be listed for the second initiator device. You can use the cpiscsi command to duplicate the iSCSI target device configuration.