Software Manual

The error rate tests for each direction cover different parts of the tape and are run at different
speeds, as shown in “Multiple tests run in each direction” (page 30). This allows the test to
characterize the drive for each direction, testing each set of heads.
Figure 11 Multiple tests run in each direction
The pass/fail criteria are the same as for the support ticket — the drive must be able to write high
quality data using no more than 20% additional tape to do so. Note that a drive will still work
well even if it needs 50% additional tape but the figure of 20% is used to allow for a little wear
and still leave a great deal of margin.
The output shows the characterization of the drive, first by tape speed and then by direction.
||_ 1.8 m/sec. tape speed:Effective capacity:94.8% Margin: 98.6% (3.0/3.0 GB written using 170.4 meters of
tape)
||_ Channel variation: 0.0% Channel variation margin: 100.0%
||_ Offtrack count: 0 CCQ rewrite percent: 0.1%
||_ 2.1 m/sec. tape speed:Effective capacity:94.8% Margin: 98.4% (3.0/3.0 GB written using 170.5 meters of
tape)
||_ Channel variation: 0.0% Channel variation margin: 100.0%
||_ Offtrack count: 0 CCQ rewrite percent: 0.1%
||_ 2.4 m/sec. tape speed:Effective capacity:94.7% Margin: 98.1% (3.0/3.0 GB written using 170.6 meters of
tape)
||_ Channel variation: 0.0% Channel variation margin: 100.0%
...
...
||_ 3.5 m/sec. tape speed:Effective capacity:94.7% Margin: 98.4% (3.0/3.0 GB written using 128.0 meters of
tape)
||_ Channel variation: 0.0% Channel variation margin: 100.0%
||_ Offtrack count: 0 CCQ rewrite percent: 0.1%
||_ 3.8 m/sec. tape speed:Effective capacity:94.6% Margin: 98.5% (3.0/3.0 GB written using 128.1 meters of
tape)
||_ Channel variation: 0.0% Channel variation margin: 100.0%
||_ Offtrack count: 0 CCQ rewrite percent: 0.1%
||_ 4.2 m/sec. tape speed:Effective capacity:94.6% Margin: 98.4% (3.0/3.0 GB written using 128.1 meters of
tape)
||_ Channel variation: 0.0% Channel variation margin: 100.0%
||_ Offtrack count: 0 CCQ rewrite percent: 0.1%
||_ forward direction:Effective capacity: 95.1% Margin: 100.0% (10.3/10.3 GB written using 594.6 meters of
tape)
||_ Channel variation: 0.0% Channel variation margin: 100.0%
||_ Offtrack count: 0 CCQ rewrite percent: 0.1%
||_ reverse direction:Effective capacity: 94.3% Margin: 96.6% (10.3/10.3 GB written using 599.5 meters of tape)
||_ Channel variation: 0.0% Channel variation margin: 100.0%
||_ Offtrack count: 0 CCQ rewrite percent: 0.1%
||_Overall drive margin:98.3%
||_Worst-case margin (reverse direction):96.6%
Each characterized speed or direction shows:
• Effective capacity — the proportion of tape used that contains the written data. There is a
theoretical possibility of 100%, but some redundancy is to be expected. Anything over 50%
shows a working drive. The pass level is 80%.
• Margin — normalizes the effective capacity to between 0% and 100% such that greater than
0% is a pass and 100% is the realistic maximum.
30 Tests and utilities