6-6 Troubleshooting and Diagnostic 62-0162-01
Why the Use Cleaning Tape LED Gets Turned ON
The Use Cleanin
g
Ta
p
e LED will be turned on whenever the
drive has determined that low level error performance has
degraded to a point where drive head cleaning is absolutely
required. It does this by counting the number of C3 (soft)
errors as well as the RAW (Read After Write) errors over a
number of Mbytes. When a predetermined error rate
threshold is reached, the drive displays the warning. Some
drives display the warning after a specified number of hours
of tape motion have been logged. When a tape is loaded, it
may take several minutes for the indication to come on
because the drive will wait for a specific number of bytes to be
written. A hard (non-recoverable) error will cause the
warning to be displayed immediately.
The most common reasons that the Use Cleanin
g
Ta
p
e LED
gets turned on for, in order of highest rate of occurrence, are
listed below:
• Dirty ("Stained") heads.
A cleaning cycle must be executed to clear this indication.
• Worn tape.
DLT tapes are rated at 500,000 passes. Applications that
overwrite small blocks of data cause "shoe shining" of the
tape against the head and will reach the 500,000 passes
sooner than might be expected.
• Bad environment.
Data errors result from a number of factors, each of which
subtract from the margin between good data recovery
and an error. Electrical or magnetic interference can
decrease this margin. High levels of dust contamination,
high humidity, and heat can also be significant factors.
Placing a CRT monitor on top of, or directly next to, a
4000/7000DLT Series should always be avoided.
• Worn heads.
The tape heads will eventually wear out causing the time
between cleanings to get shorter and shorter. Tape head
failure is usually predicted at about 12% of the MTBF
rating (10,000 hours).
• Defective drive.
Drive amplifier settings could be off, causing error rate
degradation. The drive could simply have failed.