Persistent Naming Support
Persistent naming support is used to ensure that attached devices are always configured with the same logical name based on the SCSI ID, LUN ID, and host bus adapter (HBA), even when the system is rebooted.
When the AIX® operating system is booted, the HBA runs a device discovery and assigns a default logical name to each device found in a sequential order. If there are three tape drives attached to a parallel SCSI adapter, each with a LUN ID of 0 and a target address of 0, 1, and 2, the HBA initially configures them as Available with the following logical names.
rmt0 target 0, lun 0 Available rmt1 target 1, lun 0 Available rmt2 target 2, lun 0 Available
- rmdev -dl rmt1 - rmdev -dl rmt2
On the next reboot, if the existing rmt1 target 1 device is powered off or not connected, the HBA initially configures two devices as Available with the following logical names:
rmt0 target 0, lun 0 Available rmt1 target 2, lun 0 Available
If the previous rmt1 target 1 device is powered on after reboot and the cfgmgr command is run, the HBA configures the device as rmt2 instead of rmt1.
rmt2 target 1, lun 0 Available
This is one example, but there are other cases where the logical names of devices could change when the system is rebooted. For applications that need a consistent naming convention for all attached devices, it is accomplished with persistent naming support by defining a unique logical name (other than the AIX default names) that are associated with the specific SCSI ID, LUN ID, and HBA that the device is connected to.