This counter reports the number of times a read error occurred while Automatic Data Recovery was copying data from this physical drive to another drive during the reference time, which halts the recovery process when it happens. An admin treats any nonzero value here as confirmation that the source physical drive has genuinely failed, since a healthy source drive wouldn't cause recovery reads to error out. For example, a nonzero count during an attempted rebuild would prompt the admin to run diagnostics to verify the drive is indeed bad rather than retry the recovery.