User's Guide

Page 64 DDS-4 SCSI Interface Manual, Rev. B
The total errors corrected count is incremented each time the drive recovers from a
read error. This count includes the reread count and all C3 ECC errors that could be
corrected.
Note: This count does NOT include any frames read that were rewritten
when the tape was recorded.
The total correctable ECC error count is incremented each time the ECC process
corrects one to two erroneous tracks read from the tape. For performance reasons,
the ECC process corrects errors rather than retrying if the tracks in error are less
than three; otherwise, a reread is performed.
Note: This count is a count of the correctable C3 errors ONLY. It does NOT
include the C1 or C2 ECC errors normally encountered while reading DDS-
formatted cassettes.
The total bytes read count is incremented by the size of each group (in bytes) that is
successfully read from the tape. This count includes overhead bytes (as defined by
the DDS format specification) that were read from the group.
However, this count does NOT include any additional rewritten frames that were
read nor any rereads. Also, it is greater than the count of read data bytes
transferred.
The total uncorrectable errors count is a tabulation of the times the drive could not
correct a read error by any means (including the reread retry limit being exceeded).
The rereads since last write-type operation count is similar to the total reread count
(0002) except the counter is set to 0 in two cases:
• When the operation is changed to a write-type operation.
• When a rewind operation is performed.
Tape Alert Log Page (page 2Eh)
The Tape Alert Log page provides information about errors and status of the drive
and media in the form of a flag for the supported Tape Alert Flags. The DDS-4 and
DAT 72 drive autoloader conform to the Tape Alert v3.0 Standard. The Tape Alert
Log page can only be accessed by the Log Sense commands, there are no Log
Select actions defined in the Tape Alert specification. The log page is used in
conjunction with the Tape Alert Mode Page that controls the action taken by the
drive when a flag is set and sets various other control mechanisms of the Tape Alert
system. A flag is set whenever the condition for setting the flag exists. There are
three types of flags, Informational, Warning, and Critical. The type of flag depends
upon the severity of the condition that sets the flag. Flags are cleared on the
following conditions:
• At drive power on
• When the TapeAlert Log page is read
• When specified corrective action has been taken (such as using a cleaning
cartridge)
• On a SCSI bus reset or bus device reset message
• On Log Select reset (note that the recommended action on receiving Log Select
for the TapeAlert Log page is to reject the command with an error