Figure 28. Tolerance On Seamless Appending - Seagate STD124000N Product Manual

Chapter 6
Page 56
The following rules are for the DDS-3 format for a seamless append:
1. There should be one frame between Frame A and Frame B. For example, if
frame A has an absolute frame number (AFN) of n , then Frame B should have
an AFN of n + 2 .
2. The frame written between Frames A and B should be contiguous with Frame
A. For example, no unrecorded space between A and B is permitted.
3. There should be a minimum of one amble frame between Frames B and C. For
example, if Frame B has an AFN of n + 2 , then Frame C should have an AFN of
n + 4 minimum. No unrecorded space, physical discontinuity or AFN
discontinuity or repetition is allowed between frames B and C.
Frame A
(AFN = n ) (AFN = n + 1)
Ideal tape
centerline
Tape reference edge

Figure 28. Tolerance on Seamless Appending

The following rules are for the DDS-3 format for a nonseamless append:
1. The distance between Frame A and Frame B should allow for a minimum of one
and a maximum of 11 frames. No unrecorded space is allowed between Frame
A and Frame B.
2. Discontinuities and repetitions of AFN are permitted between Frame A and
Frame B provided that, where Frame A has an AFN of n ,
– All frames have an AFN greater than n, and
– Frame B has an AFN of n + 2 minimum and n + 12 maximum.
Frame Frame B
(AFN = n + 2)
X
Tape Formats
Direction of tape motion
DAT Drives