[Bug-ddrescue] Seem to be getting bad/corrupt data from ddrescue, no errors being reported

[Michael Darling]

Hi,

I seem to be getting corrupt information from a hard drive, although ddrescue isn't reporting any errors.  Drive originally had bad heads, performed head swap in a cleanroo.  Drive is recognized after head swap, but has differences on data being read.

Any ideas on what's going on?  Any way to proceed and be confident in the data written out?

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address@hidden dataRecovery]# ddrescue --direct --max-size=1Mi /dev/sdg try1.img try1.img.logfile


Press Ctrl-C to interrupt
Initial status (read from logfile)
rescued:         0 B,  errsize:       0 B,  errors:       0
Current status
rescued:    1024 kB,  errsize:       0 B,  current rate:     1228 B/s
   ipos:    983552 B,   errors:       0,    average rate:    24742 B/s
   opos:    983552 B
Finished                
address@hidden dataRecovery]# ddrescue --direct --max-size=1Mi /dev/sdg try2.img try2.img.logfile


Press Ctrl-C to interrupt
Initial status (read from logfile)
rescued:         0 B,  errsize:       0 B,  errors:       0
Current status
rescued:    1024 kB,  errsize:       0 B,  current rate:     1228 B/s
   ipos:    983552 B,   errors:       0,    average rate:    26044 B/s
   opos:    983552 B
Finished                
address@hidden dataRecovery]# diff try1.img try2.img
Binary files try1.img and try2.img differ
address@hidden dataRecovery]# diff try1.img try2.img --text |wc -l
6148


from 'heme try1.img' :
000165D0:    12 00 00 00 00 10 24 00 FF 01 1F 00 01 05 00 00   ......$.........
000165E0:    00 00 00 05 15 00 00 00 81 77 D9 74 A9 31 43 40   .........w.t.1C@
000165F0:    8A A7 32 3F EC 03 00 00 01 05 00 00 00 00 00 05   ..2?............
00016600:    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00   ................
00016610:    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00   ................
00016620:    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00   ................

from 'heme try2.img' :
000165D0:    12 00 00 00 00 10 24 00 FF 01 1F 00 01 05 00 00   ......$.........
000165E0:    00 00 00 05 15 00 00 00 81 77 D9 74 A9 31 43 40   .........w.t.1C@
000165F0:    8A A7 32 3F EC 03 00 00 01 05 00 00 00 00 00 05   ..2?............
00016600:    00 00 00 05 20 00 00 00 20 02 00 00 01 01 00 00   .... ... .......
00016610:    00 00 00 05 12 00 00 00 00 00 00 00 00 00 00 00   ................
00016620:    12 AB B6 1C EC 01 00 00 20 C6 00 00 00 00 00 00   ........ .......