M2488 PRODUCT GUIDE

TAPE UNIT PARAMETERS

 

Table 5-5.

Error Recovery and Reporting Parameters Field Description (Continued)

 

 

 

 

 

BYTE

 

BIT

VALUE

DESCRIPTION

 

 

 

 

 

2

 

2

1

When the Post Error (PER) bit is set to one, this bit indicates that the target enables

 

 

 

 

reporting of CHECK CONDITION status for recovered errors, with the appropriate

 

 

 

 

sense key being returned. CHECK CONDITION status occurs during the data

 

 

 

 

transfer depending either on the DTE bit value or if an unrecoverable error

 

 

 

 

occurred. If multiple errors occur, the REQUEST SENSE data reports the block

 

 

 

 

address of either the last block on which recovered error occurred or of the first

 

 

 

 

unrecovered error. If this bit is 0, the DTE bit must also be 0.

 

 

 

0

When PER is set to zero, this bit indicates that the target does not create the

 

 

 

 

CHECK CONDITION status for errors recovered within the limits established by

 

 

 

 

the other error recovery flags. Recovery procedures exceeding the limits established

 

 

 

 

by the other error recovery flags are posted accordingly by the target. The transfer

 

 

 

 

of data may terminate prior to exhausting the transfer length depending on the error

 

 

 

 

and the state of the other error recovery flags.

 

 

 

 

The PER bit is reported as changeable on a MODE SENSE command, and the

 

 

 

 

default value is zero.

 

 

 

 

 

2

 

3

1

When the Enable Early Recovery (EER) bit is set to one, this bit indicates that the

 

 

 

 

target enables the use of the most expedient form of error recovery, such as error

 

 

 

 

correction, before applying retries. Seek or positioning retries and the recovery pro-

 

 

 

 

cedure retries of the message system are not affected by the value of this bit.

 

 

 

0

When EER is set to zero, this bit indicates that the target exhausts the defined retry

 

 

 

 

limit prior to enabling error correction.

 

 

 

 

The EER bit is reported as not changeable on a MODE SENSE command and the

 

 

 

 

default value is one.

 

 

 

 

 

2

 

5

1

When Transfer Block (TB) is set to one, this bit indicates that the failing data block

 

 

 

 

(recovered or unrecovered) is transferred to the initiator.

 

 

 

0

When TB is set to zero, this bit indicates that an unrecovered failing data block is

 

 

 

 

not transferred to the initiator. Recovered data blocks are always transferred, regard-

 

 

 

 

less of the values of the TB bit.

 

 

 

 

In both cases the block reported in the Request Sense data is the block in error, not

 

 

 

 

the preceding block.

 

 

 

 

The TB bit is reported as changeable on a MODE SENSE command, and the

 

 

 

 

default value is zero.

 

 

 

 

 

3

 

0-7

>0

A non-zero value in Read Retry Count field specifies the number of times that the

 

 

 

 

target attempts its recovery algorithm during a read operation before an unrecover-

 

 

 

 

able error is reported.

 

 

 

0

A value of zero in this field indicates that the target shall not use its recovery algo-

 

 

 

 

rithm during read operations.

 

 

 

 

The Read Retry Count field is reported as changeable, and the default value is 10h.

 

 

 

 

 

8

 

0-6

>0

A non-zero value in the Write Retry Count field specifies the number of times that

 

 

 

 

the target attempts its recovery algorithm during a write operation before an unre-

 

 

 

 

coverable error is reported.

 

 

 

0

A value of zero in this field indicates that the target shall not use its recovery algo-

 

 

 

 

rithm during write operations.

 

 

 

 

The Write Retry Count field is reported as changeable and the default value is 10h.

 

 

 

 

 

8

 

7

 

The meaning of this bit is dependent upon the setting of the WRTY bit in Mode

 

 

 

 

Page 00. With WRTY set to 0, this bit is defined as the MSB of the Write Retry

 

 

 

 

Count. Otherwise:

 

 

 

0

Report permanent error when count in bits 0-6 is exhausted.

 

 

 

1

Do not report error, continue writing next block. CAUTION: This setting may pro-

 

 

 

 

duce unreadable tapes.

 

 

 

 

 

April 1997

CG00000-011503 REV. A

5-5

Page 241
Image 241
Fujitsu M2488 manual State of the other error recovery flags