This read-only Counter64 reports the number of bytes read from a given storage device since the Synology NAS last booted, as a 64-bit counter that avoids the wraparound issues of the 32-bit spaceIONRead on high-throughput or long-uptime systems. Admins prefer this counter over its 32-bit equivalent when polling less frequently or when disk throughput is high enough to wrap a 32-bit value between polls. For example, a NAS with sustained multi-gigabyte-per-second read throughput would need this 64-bit counter to get accurate byte totals over a full day's uptime.