IBM TS2340 User Guide - Page 51

AIX Device Driver (Atape) The installation default is Off (no trailer labels). Media Parameters The ability to set or change media parameters is a tape diagnostic and utility function, refer to Chapter 10, "IBM Tape Diagnostic Tool (ITDT)," on page 259 or "AIX System - Tape Utility Program (tapeutil)" on page 362. The media parameters can be queried and set by ITDT or the tape diagnostic and utility function using the Query/Set Parameters option in the window. These parameters cannot be set or changed by the configuration procedures. The media parameters are: v Capacity scaling v Logical write protect v Volume ID for logging Capacity Scaling This parameter sets the capacity or logical length of the current tape on IBM TotalStorage Enterprise Tape System 3590, IBM TotalStorage Enterprise Tape System 3592, or Magstar MP tape subsystems. By reducing the capacity of the tape, the tape drive can access data faster at the expense of data capacity. Capacity scaling can be set at 100% for the entire tape (which is the default) or set at 75%, 50%, or 25% of the tape or any device specific hexadecimal value. For example on IBM 3592, to change capacity scaling from a 300 GB format tape (100%) to a 60 GB format tape, select the capacity scaling option, then select the option to enter a hexadecimal value and enter 35. Capacity scaling remains with the tape across mounts until it is changed. Notes: 1. The tape position must be at the start of the tape to change this parameter from its current value. 2. Changing this parameter destroys any existing data on the tape. 3. Attempting to set capacity scaling that is not supported by a device or the current media loaded always returns 100% and cannot be changed. For example, 60 GB media for the IBM 3592 cannot be capacity scaled and is always 100%. Logical Write Protect This parameter sets or resets the logical write protect of the current tape on IBM TotalStorage Enterprise Tape System 3590, IBM TotalStorage Enterprise Tape System 3592, or Magstar MP tape subsystems. The three types of logical write protect are: associated protect, persistent protect, and write-once read-many (WORM) protect. Associated protect remains only while the current tape is mounted or associated with the tape drive. It is reset when the tape is unloaded or the tape drive is reset. Persistent protect remains or persists with the tape across mounts until it is reset. WORM protect also remains with the tape across mounts, but (unlike persistent protect) it cannot be reset on the tape. After a tape is WORM protected, it can never be written on again. Chapter 3. AIX Tape and Medium Changer Device Driver 33