Quantum DLT 2000 Handbook page 71

centage of recorded data, and in larger blocks (measured in num-
ber of consecutive bytes) to prevent data loss.
During write operations, the DLTtape drive assures that the data
written is correct by performing a read after write. If an error is
detected, the drive rewrites the data block (see Figure 6-3) further
down the tape until the read-after-write check validates that the
block is now correct. In addition, the drive records powerful Reed-
Solomon ECC blocks on tape.
During read operations, if an error occurs, DLTtape drives recover
the data using powerful ECC code. DLTtape drives can recover up
to four bad blocks of data within a 20-block entity. At a recording
density of 62.5Kbits per inch, four consecutive blocks translates to
two inches of DLTtape media. That means that, even if as much as
two consecutive inches of tape are damaged on a single track, a
DLTtape drive can recover the data.
Conclusion
Comparing the specifications for the DLTtape system to the specifi-
cations for other technologies reveals significant benefits in a num-
ber of areas, including overall capacity, capacity per cartridge, and
transfer rate. In other areas, primarily reliability, a comparison of
specs shows that the underlying DLTtape technology results in an
order-of-magnitude advantage. Leadership in speed and capacity are
certainly important, but it is in the area of reliability that the specifi-
cations reveal the most dramatic differentials between the DLTtape
system and competitive products.
Next, we'll take a look at DLTtape media and discover the benefits
of Quantum DLTtape cartridges.
6.8 DEMYSTIFYING TAPE DRIVE SPECS