But a drive that goes missing has been cured a few times (more than a few) by me performing the following procedure. I will not debate if one thinks its right, wrong, or if one can skip a step. Its my way to get away from trouble.
1. Set the drives in question to CS or Cable Select.
2. Fit a new 80 conductor IDE cable on said channel. This can be a 1.19 item. If the owner balks at this cost, then it's best we send them away.
3. Update the FIRMWARE of the drives on that channel per the maker's instructions.
Usually this clears up the vanishing drives. If not, we swap out the drive and re-test.
Bob

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