The operating parameters for the tape drive and device driver are set and changed by configuration parameters. The installation defaults are provided for all
parameters initially. The AIXsmitcommand is used to set these parameters when configuring a device or to change these parameters. The AIXchdevcommand is used to change the configuration parameters.
The configuration parameters are used to set the operating mode of the tape drive and device driver when a device is opened. These parameters are queried by an application. Some parameters can be temporarily changed during the open subroutine by an application, but they are always restored to the configuration values when a device is closed. The configuration parameters are:
v Alternate Pathing v Autoloading
v Emulate autoloader (359x devices only) v Block size
v Buffered mode (359x devices only) v Compression
v Fail degraded media (359x devices only) v Logging
v Maximum size of the log file v New logical name
v Read error recovery time (359x devices only) v Record space mode
v Rewind immediate v Trailer labels
Alternate Pathing
This parameter enables or disables the path failover support when a device is configured. “Data Path Failover and Load Balancing Support for Tape Drives” on page 39 for a description of the path failover and failover support.
The installation default is Off (path failover is not enabled).
Autoloading
This parameter enables the autoloading feature of the device driver. It is used with the autoloading capability of the autoloader, ACF, ACL, or CSL installed on the tape device.
Note:The autoloading feature is not supported on the IBM 3584 UltraScalable Tape Library and the IBM 3583 Ultrium Scalable Tape Library with more than one IBM 3580 Ultrium Tape Drive installed.
Note: The autoloading feature is supported only on the following device types and configurations:
v IBM 3490E Models C11, C22, E01, E11, F01, and F11
v IBM TotalStorage Enterprise Tape System 3590, Models B11, E11, and H11 v IBM Magstar MP 3570 Models B01, C01, B11, and C11
v IBM Magstar MP 3570 Models B02, B12, C02, and C12 (configured in split mode only)
Do not enable autoloading if one of the following conditions is true:
v The device is used by an application that provides library medium changer support for the IBM 3581 or IBM 3583.
v The device is installed in a 3494 Enterprise Tape Library. v The device is used by an application with stack loader support. v The application is MKSYSB.
v The tapes being read were not written using the autoloading feature.
Tapes created with AUTOLOAD=YES may not be readable in configurations without Atape autoload enabled, or on other UNIX®operating systems, or on device types/models that are different from the backup device type/model. If the parameter is set to on, then the tape stacker acts as one large virtual tape. During a read, write, or forward space file operation, no end of tape is detected by the application. When the end of tape is reached, the device driver automatically rewinds and unloads the tape, loads the next tape, then continues reading or writing the next tape. The following conditions are required to use this feature: v The autoloading parameter must be set to On.
v The cartridge stacker must be loaded with one or more tapes.
v The ACF, ACL, or CSL must be set to Automatic, System, or Random mode.
This feature allows multivolume backups (with commands such as tar) without prompting for a volume change.
The installation default is Off (no autoloading).
Emulate Autoloader
This parameter controls how the device driver operates when the ACF on the IBM TotalStorage Enterprise Tape System 3590, the IBM Magstar MP tape device, or the IBM 3490E Model Fxxis set toRandommode. If this parameter is set to On and the ACF is in Random mode, the device driver emulates an autoloading tape drive. When an unload command is sent to the device driver to unload a tape, the tape is unloaded, returned to the magazine, and the next tape in the magazine is loaded automatically into the tape drive. If this parameter is set to Off, the normal unload operation occurs, and the tape remains in the drive.
The emulate autoloader parameter can be used for legacy applications written for the IBM 3490E Automated Cartridge Loader (ACL) when the IBM TotalStorage Enterprise Tape System 3590, the IBM Magstar MP 3570, or the IBM 3490 Model F autoloader is set toRandommode. This eliminates the need to re-configure the autoloader of the deviceRandomorAutomaticoperation.
The installation default is Off (do not emulate autoloader).
Note: On IBM Magstar MP 3570 Models B02, C02, and C12, this feature is
supported only when the two drives are configured inSplitmode, or inBase mode with only one drive configured and available to AIX. This feature does not work in Base mode if both drives are in the available state to AIX.
Block Size
This parameter specifies the block size used for read and write operations. A value of zero is the variable block size. Any other value is a fixed block size.
The installation default is zero (use variable length) exceptfor the IBM 7332 4mm Tape Cartridge Autoloader, for which the default is a fixed block size of 1024 bytes.
Buffered Mode
When a write command is processed, the data is either stored directly on the physical tape or buffered in the tape device. Buffering can increase the device performance.
The installation default is On (use Buffered mode).
Compression
Hardware compression is implemented in the device hardware. This parameter turns the compression feature On and Off. If compression is enabled, then the effective performance can increase based on the compressibility of the data. The installation default is On (use compression).