Command fault when analyzing a CMI 6426-S

[Chris Tersteeg]

Just finished up a Rev D board this weekend and has been working great. Thanks again David for the hard work on this project. Started dumping a few working drives attached to IBM 5170's.  A Seagate ST-4038 worked fine, but when I tried the same --analyze on a CMI 6426-S I got the following below.  I can successfully dump an emulation file from it by manually specifying the cylinders and heads without analyze, but it also didn't report any sectors marked bad like the Seagate did when it was dumped.  Could just be a bad drive (these are notorious for failing), but figured I post the results here.

debian@BeagleBone:/opt/mfm/mfm$ mfm_util --version
Version 4.33

debian@BeagleBone:/opt/mfm/mfm$ setup_mfm_read
Rev C or D Board
debian@BeagleBone:/opt/mfm/mfm$ mfm_read --analyze --emulation_file ibm-5170-type2-emulation2 --extracted_data_file ibm-5170-type2-data2
Board revision C detected
Found drive at select 1
Drive RPM 3573.5
Matches count 34 for controller WD_1006
Header CRC: Polynomial 0x1021 length 16 initial value 0xffff
Sector length 512
Data CRC: Polynomial 0x140a0445 length 32 initial value 0xffffffff
Selected head 8 found 0, last good head found 3
Read errors trying to determine sector numbering, results may be in error
Number of heads 4 number of sectors 17 first sector 1
Interleave (not checked): 1 7 13 2 8 14 3 9 15 4 10 16 5 11 17 6 12
Drive supports buffered seeks (ST412)
No sectors readable from cylinder 615
Command 7 fault 300 status 34
Write fault
Not Seek complete
Not Index
Not Ready
Drive selected

[David Gesswein]

On Sun, Feb 02, 2025 at 03:11:59PM -0800, Chris Tersteeg wrote:
> No sectors readable from cylinder 615

> *Command 7 fault 300 status 34*

> Write fault
> Not Seek complete
> Not Index
> Not Ready
> Drive selected

This says the drive went not ready. Its asserting write fault. It may not like
trying to step past last cylinder which I do to determine size. I can't
determine exactly where the fault occurs. If we want to try to fix this I
can send code with more prints to determine where its generating the
error.

> I can successfully dump an emulation file from it by manually specifying
> the cylinders and heads without analyze, but it also didn't report any
> sectors marked bad like the Seagate did when it was dumped. Could just be
> a bad drive (these are notorious for failing), but figured I post the
> results here.
>

Drive is likely fine. You can use mfm_util --analyze --emu filename --ext /tmp/t
to check the emulator file for errors. If you do have errors and want to try
the read with retries to see if you can get less errors you can copy
and paste the command line it print after
Command line to read disk:
into mfm_read.
adding file to create etc.