Sometimes, a raw flux dump will have bad or missing sectors. This leads to output from disk-analyse that will have missing blocks, which can lead to an unusable, truncated image.

Example of a standard IBM 3740 8" disk (77 tracks of 26 128-byte sectors) with this issue:

$ disk-analyse -v -i --format=ibm --ss=0 --end-cyl=76 unk02.hfe unk02.img
T0.0-61.0: IBM-FM DD (26 128-byte sectors, 3328 bytes)
T62.0-63.0: IBM-FM DD (25 128-byte sectors, 3200 bytes)
T64.0-67.0: IBM-FM DD (26 128-byte sectors, 3328 bytes)
T68.0: IBM-FM DD (25 128-byte sectors, 3200 bytes)
T69.0-75.0: IBM-FM DD (26 128-byte sectors, 3328 bytes)
T76.0: IBM-FM DD (25 128-byte sectors, 3200 bytes)
$ ls -la unk02.img
-rw-r--r-- 1 1001 1001 255744 Nov 29 16:49 unk02.img
$ dc
26 128 * 77 * p
256256
255744 - p
512
128 / p
4

In this case, the OS knew there are 4 bad blocks and mapped around them, but the truncated image produced by disk-analyse cannot be used by the system (or its emulation).

It would be nice in these cases to replace the bad or missing blocks with a static byte - for instance, e5 or 00. Otherwise, hex editing of the file is required to produce a usable sector dump.