Specifications

ATAPI For Streaming Tape QIC-157 Rev B

6.8.6.38.2.Error Counter Page (Write)

This section defines the parameter codes for the Error Counter Page (Write), page code 02h). Table 6-

27 defines the counters and their use.

The following techniques can be used to correct errors detected when writing to tape.

1. Rewrites. If a bad block is detected during the read after write operation, the block will be

rewritten until it reads correctly or until the maximum rewrite count is reached. Note that the

maximum rewrite count is defined by the physical tape format. Rewrites facilitate tape streaming.

2. Tape re-positioning. Re-positioning during write errors applies only to rewritable data frames.

NOTE: The distance between the write and the read heads may be large compared to the data blocks,

therefore, there may be several blocks between the block that is accessed by the write head and the

block that is accessed by the read head. This means that for a write retry without re-positioning several

blocks may be discarded.

Table 6-27 Parameter Codes for Error Counter Page (Write) - Page Code 02h

Code Description

0000h Number of rewrites. Blocks that follow the bad block but precede the last block written will

also be re-written, however, these blocks shall not be included in this count.

0002h Number of re-positions. This count is incremented when tape re-positioning is performed due

to an error when attempting to write a re-writable frame. This counter is only used with tape

formats which support overwrite.

0003h Total number of blocks recovered.

0006h Number of physical blocks not recovered.

NOTES: A frame is in error if any one block, or any number of blocks within the frame cannot be

read. The term "blocks" refers to physical blocks on tape.