tapes. You will never need most of them. But if you do need some old
tapes from last year, or 5 years ago, or just last week, you would have
a major problem if you had changed backup platforms. That is gen-
erally not the case with DLTtape technology. A cartridge recorded on
a DLT 2000 drive three or four years ago can be read on a DLT 4000
drive today. You can put a DLTtape IV cartridge in a DLT 4000 drive
today, fill it with data, and two years from now you will be able to
read it on a DLT 8000 drive (see Figures 4-5 and 4-6). All DLTtape
drives up to the DLT 4000 drive use a similar head design and record-
ing pattern that makes possible compatibility among drives.
However, the DLT 7000 and DLT 8000 drives use a new recording
pattern, Symmetric Phase Recording. The read/write head of the
DLT 7000 and DLT 8000 drives tilt forward and back (see Figure 4-5)
to achieve higher track density. When a DLTtape cartridge that has
been recorded on a DLT 4000 drive, for example, is inserted in a
DLT 8000 drive, the drive automatically detects the difference in
recording pattern. The DLT 8000 drive then automatically adjusts its
read/write head (Figure 4-6) to a vertical position that enables it to
read the older DLTtape cartridge.
WHY CUSTOMERS WANT DLTtape SYSTEMS
4.10
Forward
Write Cores
Reverse
Write Cores
Reader Cores
Figure 4-4 DLT 7000/DLT 8000 Read/Write Head
tilts
back and forth to record at highest data density, yet it can still read
older formats by assuming vertical position shown here.