Forward SPACE Block
When an Abort is executed during a forward space block operation, the read pointer is synchronized to the first start block found, and data is read until the buffer is full. Check Condition status is sent to the initiator. The Valid bit is set to 1, and the Information bytes contain the number of blocks not yet found.
For a forward SPACE block operation, the final position at the end of the Abort can be determined by the following formula:
Current Block = Start Block + Space Request − Information Bytes
Backward SPACE Block
During a backward space block operation, the EXB 8200 delays the execution of the Abort message until it finds the next filemark or LBOT, or until the reverse tape motion of the backward space block operation is completed.
For a backward SPACE block operation, no formula can be used to determine the final position at the end of an Abort. The Valid bit may be set, but the Information bytes are not valid.
After an Abort during a backward SPACE block operation, the initiator should issue the REWIND command and prepare for the next command.
19.4 Errors Reported
In addition to the situations listed in Section 4.4, the SPACE command results in an error condition under the following circumstances:
Filemark Encountered While Spacing Over Blocks
When the EXB 8200 encounters a filemark while spacing over logical blocks, the space operation is terminated and the tape is positioned as follows:
■ If the filemark is detected during a forward space operation, the tape is positioned on the EOT side of the filemark.
19 SPACE (11h)
■ If the filemark is detected during a backward space operation, the tape is positioned on the BOT side of the filemark.
Check Condition status is sent to the initiator, and sense data is created with the sense key set to No Sense (0h) and the FMK bit set to 1. The Valid bit is set to 1, and the value for the Information bytes is calculated.
The Information bytes contain the difference between the Count in the CDB and the number of blocks the EXB 8200 spaced over before encountering the filemark.
PEOT Reached
When the EXB 8200 encounters PEOT while spacing over filemarks or blocks, the space operation is terminated. Check Condition status is sent to the initiator. Sense data is created with the sense key set to Medium Error (3h) and the EOM bit and PEOT bit set to 1. The Valid bit is set to 1 and the value for the Information bytes is calculated.
The Information bytes contain the difference between the Count in the CDB and the number of blocks or filemarks the EXB 8200 spaced over before reaching PEOT.
PBOT or LBOT Reached
When the EXB 8200 encounters PBOT or LBOT while spacing over filemarks or blocks, the space operation is terminated and the tape is positioned at LBOT. Check Condition status is sent to the initiator. Sense data is created with the sense key set to No Sense (0h) and the EOM bit and LBOT bit set to 1. The Valid bit is set to 1 and the value for the Information bytes is calculated.
The Information bytes contain the difference between the Count in the CDB and the number of blocks or filemarks the EXB 8200 spaced over before reaching PBOT or LBOT.
Blank Tape Encountered While Spacing Over Blocks
When the EXB 8200 encounters blank (unrecorded) tape during a space block operation, the operation is terminated. Check Condition status is sent to the initiator, and sense data is created with the sense key set to Blank Check (8h).
The Valid bit is set to 1, and the value for the Information bytes is calculated.
The Information bytes contain the difference between the Count in the CDB and the number of blocks the EXB 8200 spaced over before reaching blank tape.
19 SPACE (11h)
Incorrect Filemark Detected
When the EXB 8200 is executing the space filemark operation and miscounts the number of filemarks encountered, Check Condition status is sent to the initiator. Sense data is created with the sense key set to EXABYTE (9h) and the FMK bit set to either 0 or 1. The Valid bit is set to 1 and the value for the Information bytes is calculated.
The actions you can take to correct the position depend on the value of the FMK bit, the direction of the space operation, and the value of the
Information bytes.
If the FMK bit is 0, contact your vendor for assistance. If the FMK bit is 1, perform the appropriate steps below, based upon the direction of the space operation:
Backward Space Filemark Operation For a backward space filemark operation, perform one of the following actions depending on the value of the Information bytes:
■ If the value of the Information bytes is positive, execute a forward SPACE filemark command using the value of the Information bytes. Then,
execute a backward SPACE filemark using a value of 1.
■ If the value of the Information bytes is negative, execute a backward SPACE filemark command using the value of the Information bytes.
Forward Space Filemark Operation For a forward space filemark
operation, perform one of the following actions depending on the value of the Information bytes:
■ If the value of the Information bytes is positive, execute a forward SPACE filemark command using the value of the Information bytes.
■ If the value of the Information bytes is negative, execute a backward SPACE filemark command using the value of the Information bytes.
Then, execute a forward SPACE filemark command using a value of 1.
Tape Unloaded but Still in the EXB-8200
When the data cartridge has been inserted and the door closed with the autoload feature disabled, or when the data cartridge has been unloaded with the prevent medium removal feature enabled, the SPACE command results in a Check Condition status with the sense key set to Not Ready (2h).
19 SPACE (11h)