ASSIGN
Attaches tape units to the terminal, assigns tape parameters to the units, and assigns a channel identity, if required.
Command Class
TCL-I command.
Syntax
ASSIGN {channel}=TAPE unit-list
Syntax Elements
channel The identity of a logical data channel to which the tape unit is attached and to which assigned parameters apply. This can be any alphabetic character from A to Z.
- If a channel is specified, the default channel is cleared.
- If no channel is specified, the parameters specified are assigned to the default channel.
unit-list The number(s) of the tape unit(s) to be used. Multiple tape device numbers must be separated by commas.
unit-list must be specified. A unit may not be assigned to two channels at the same time.
recordSize The tape record size in bytes. Default if omitted, 8000.
Note
The record size used with encrypted tape devices must be a multiple of 8.
density The tape density. This can be 800, 1600, 3200 or 6250 bpi, depending on your system, or 24, 120, 150, 320 or 525 QIC format for quarter inch cartridge tape units. The density determines the tape device used as specified in the database config file. For details, refer to Tape Definitions.
The density parameter is optional. The default is defined in the database config file.
When a density has been selected for a unit, it remains in force for any subsequent assignments until the density is redefined or the assignment is destroyed by tape detachment or log off.
buffers The number of tape buffers, in the range 1 to 10. The default is 2. The size of each buffer is equal to the record size. Most installations use the default value.
labelType The type of tape label to be written; one of the following:
2 SMA standard 80-byte label (default).
Note
If the record size is larger than 32Kbytes, a modified type 2 label is used. See Tape Labels for details.
1 Reality 50-byte label. Allows you to write tapes that can be read on early proprietary versions of Reality.
0 No label (use of this type is not recommended).
In read operations, the label type is automatically set to that found on the tape, and so this parameter does not need to be specified.
Options
L Leaves tapes loaded until all tapes have been written once. If the tape system attempts to wrap around and write on the first tape, all units are unloaded. Hence, each reel is unloaded on completion of rewind.
M Logs all tape errors, including recovered errors.
Comment
Unspecified parameters are reset to their default values.
Before using ASSIGN, you must load the tape and switch the unit on-line; otherwise the assignment may fail.
The unit remains attached until log off or until it is detached using CLEAR-ASSIGN.
The tape speed is determined by the process being carried out and cannot be independently selected. For example, the tape speed is high for file and account saves, whereas a lower speed is used for tape dumps.
The tape unit attached and the density/QIC parameter selected is determined by the tape configuration defined either in the database config file (see Tape Definitions) or using the T-DEVICE command.
Messages
If a unit has already been assigned to another channel, the following message is displayed:
Device tape n assigned to this line, but for another channel
If you attempt to perform a tape operation before attaching the tape drive the following message is displayed:
[1129] No such tape assignment exists
If you attempt to attach a tape that is already assigned to another user, the following message is displayed:
Device(s) tape n now assigned to channel m
If you attempt to attach a tape device number which is not configured on your database, the following message is displayed:
Device Tape n not on this system
Examples
:ASSIGN =TAPE 3
[1021] DEVICE(S) TAPE 3 NOW ASSIGNED,
RECORD SIZE = 31744 DENSITY = 1600 BPI
Tape unit 3 is set up as the default channel. Any other channel assignments are cleared.
:ASSIGN A=TAPE 2 SIZE=1024
[1120] DEVICE(S) 2 NOW ASSIGNED TO CHANNEL 'A',
RECORD SIZE = 1024 DENSITY = 1600 BPI
Tape 2 is assigned as channel A with a record size of 1024 and the default density of 1600 bpi. Any default channel is cleared.
:ASSIGN B=TAPE 3 SIZE=8192 DEN=1600
[1120] DEVICE(S) TAPE 3 NOW ASSIGNED TO CHANNEL 'B',
RECORD SIZE = 8192 DENSITY = 3200 BPI
Tape unit 3 is assigned as channel B with a record size of 8192 and density of 1600 bpi. This does not affect any existing assignment with a different channel identifier.
:ASSIGN A=TAPE 1,2 SIZE=1024 (L
[1120] DEVICE(S) TAPE 1 AND 2 NOW ASSIGNED TO CHANNEL A,
RECORD SIZE = 1024 DENSITY = 1600 BPI
Tape units 1 and 2 are assigned as channel A with a record size of 1024 and density of 1600 bpi. The tapes are not unloaded until all tapes have been written once and the system attempts to wrap around. This does not affect any existing assignment with a different channel identifier.