From a software perspective, the device files that are associated with the FC LUNs can be  symbolically linked to the same secondary device file based on the LUN information. This  setup ensures persistence upon discovery, even if the device’s ID on the fabric changes. Operating systems and upper-level applications (such as backup software) typically require a  static or predictable SCSI target ID for storage reliability, and for persistent device naming. An example where persistent naming is useful is a specific host that always assigns the same  device name to the first tape library and drives that it finds (Figure 6-2). 1 Persistent device naming support ensures that attached devices are always configured with  the same logical name that is based on the SCSI ID, LUN ID, and HBA. You want to be certain  that the same logical names are assigned to your device, even when the system  is restarted. For example, when the AIX OS is started, the HBA performs a device discovery and assigns  a default logical name to each device that is found, in sequential order.  Assume that an AIX system is connected to a tape library with two tape drives, with a LUN ID  of 0 and target addresses of 0, 1, and 2. The HBA initially configures them as Available with  the following logical names: Why persistent device naming matters  Figure 6-2 Persistent device name binding GLYPH<SM590000> rmt0 target 0, lun 0 Available GLYPH<SM590000> rmt1 target 1, lun 0 Available GLYPH<SM590000> rmt2 target 2, lun 0 Available 1 Reference:  http://www.storagesearch.com/datalink-art1.html 86  IBM ProtecTIER Implementation and Best Practices Guide