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disabled parity check on SCSI HDD - any negative impacts?

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First post, by feltel

Posted on 
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For my 2nd PS/2 I recently aquired a 270 MB SCSI drive (IBM-labeled Quantum LPS, https://stason.org/TULARC/pc/hard-drives-hdd/ … L-SCSI2-SE.html). The drive was jumpered to ID2, but to be bootable in an PS/2 it has to be at ID6 as far as I understand it.

Unfortunatley one of those super tiny jumpers was missing so I only was able to jumper it to ID6 by removing the jumper from the PO position. By default the jumper is being set and enables the "enable parity check" function. While the is jumper removed I did not noticed any difference and I successfully could make it boot in my PS/2. Also the SCSI drive check within the reference disk/adv diagnostics disk is without any errors.

As far as I understand it should have no consequences, but for safety's sake I want to ask if someone has an opinion on this.

Reply 1 of 1, by SirNickity

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That option is basically a compatibility feature. If you're using a card or device that doesn't support parity, you need to disable the requirement of checking it. If everything supports parity, it should generally be enabled.

Not having parity checking isn't going to immediately break things, but it does mean any errors in transmission between devices on the bus could go unnoticed. The likelihood of that happening depends on the quality of the devices, controller, and cables; the cable length; whether everything is terminated appropriately (and whether the termination is within spec); how many devices are plugged in; the electrical noise in the surrounding environment, and so on.

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