Seagate STT8000A manual Write equalization, Randomization

Tape format Chapter 6

Write equalization

The drive uses the technique of write equalization. RLL encoding has a 4:1 ratio in the minimum and maximum spacing between flux transitions. Write equalization inserts short pulses in the write current to break up the long spacing intervals. These pulses are too short to be detected in the read process but result in significant improvement in read-back resolution.

On 900 Oersted media, write equalization provides the benefit of compatibility with Magneto-Resistive (MR) heads. MR heads are prone to saturation by low frequency flux with high energy content. Equalization redistributes this energy to higher frequencies and eliminates the problem.

Randomization

To reduce problems resulting from long strings of repetitive data with a bad peak shift or amplitude characteristics, a data randomizer algorithm is used on all bytes in the data and control area of each block. This randomizing takes place prior to the encoding of the data.

STT8000A Product Manual Page 67