cpqDaPhyDrvBadTargetErrs counts how many times this physical drive performed an action that violated the SCSI-2 bus protocol, an event serious enough to force a reset of the whole SCSI bus, and is not supported on IDA, IDA Expansion, or IDA-2 controllers. Because a bus reset briefly interrupts every drive sharing that bus, a rising count on one drive can explain intermittent disruptions seen across several other drives on the same channel. For example, if several unrelated drives on one SCSI bus show brief communication hiccups, an admin would check this counter on each drive to find which one is triggering the resets.