[robespierre]

The (most likely passive) terminator you have could work sufficiently, if you connect a cable to one port on the drive and the terminator to the other.
The cable you showed will not work, it is an Apple DB25-to-C50 SCSI cable that only works with Apple type SCSI ports. The SCSI port on the Indy has 50 pins and a different (HD50-to-C50) cable is required.

https://iec.net/home/technical-informati...face-scsi/
https://iec.net/home/technical-informati...rmination/

You need a cable like this:
https://iec.net/product/scsi-cable-dm50-...oot-molded
And ideally a terminator like this:
https://iec.net/product/scsi-se-active-t...cn50-male/
although your passive terminator may work, it really is intended for slower types of SCSI systems. The Indy has a 10 MB/s Fast SCSI-2 and active termination is recommended.

When I changed to ID 1 on the scsi converter I got:
SCSI(0)disk(2)

I would guess your adapter has four jumpers labeled "ID0", "ID1", "ID2", "ID3" ?
Those need to be binary decoded to determine the actual SCSI ID selected. With no jumpers on any of them, it means ID 0. With jumpers on both 2 and 0, it means ID 5. With just a jumper on 1, it means ID 2. There are sixteen SCSI IDs, not four. However, since the Indy uses an 8-bit (narrow) SCSI bus, only eight IDs are possible.

Also note that if you are using one of the 80-to-50 pin adapters like
https://iec.net/product/scsi-adapter-id5...80-female/
that there is a risk of touching the bare pins to the exposed metal of the drive or the drive bay, which can make sparks and shut down the power: See this thread.

But you may have another problem, specific to the Indy, because it has only one SCSI bus used for both internal and external SCSI devices. As you can read on the page I linked above about termination, both ends of the bus need to be terminated. With an internal SCSI hard disk drive, one end is the drive and the other is the last external device. So you actually need two terminators.

The manual for the disk says that it cannot terminate the bus itself:

Termination is required on the Maxtor Atlas 10K V hard disk drives as they do not support on-board SCSI termination.

What you would need is to have the 50-to-80 pin adapter connected to the midpoint of the 50-pin internal ribbon SCSI cable, and put a terminator on the end of the ribbon cable. This provides termination at that end of the SCSI bus. This assumes that you have a 50-pin ribbon cable with at least 3 connectors on it.

Something like this for the terminator:
https://iec.net/product/scsi-se-active-t...id50-male/

I believe that SGI shipped Indys with a 3-connector cable that has an AMP 869574-1 active terminator permanently attached to the end.