I just knew that you (IBM) had to have done something about those stickers. They were a PITA.
Regards, Richard Schuh > -----Original Message----- > From: The IBM z/VM Operating System > [mailto:[EMAIL PROTECTED] On Behalf Of Alan Altmark > Sent: Monday, June 09, 2008 3:09 PM > To: [email protected] > Subject: Re: Backup: Twinning Tapes to Remote Tape Unit > > On Monday, 06/09/2008 at 04:06 EDT, "Schuh, Richard" <[EMAIL PROTECTED]> > wrote: > > I would hope that the use of stickers to denote EOT would have gone > > out way back in my career. > > Reflective stickers went away with the 3480. It introduced a "servo" > track that the drive uses to know the position of the tape at > all times. > EOT is at a certain physical block number, x. Every time. > Bigger tape? > Then you have a bigger value for x. The tape may be skipping > bad data blocks on the tape, but they are at known locations > and EOT still occurs at x, so the "effective length" will be > less than the "physical length". > > This is why degaussing today's tape cartridges results in a > useless tape: > the servo track is destroyed in the process. > > If you look at the sense data for today's drives, you'll see > that it contains tons of block counters AND a [fuzzy] "tape > length" indication. > > Alan Altmark > z/VM Development > IBM Endicott >
