This OID counts, in events, how many physical-layer symbol errors have been detected on this 16G Fibre Channel interface. On a Fibre Channel link carrying storage traffic, symbol errors at the physical layer can trigger link resets or I/O retries at the SCSI/FCP level, so tracking this counter helps distinguish storage-performance problems caused by the transport link from problems in the storage arrays themselves. For example, a burst of symbol errors on a 16G Fibre Channel link used for storage-array replication at the same time storage administrators report slow disk replication would point them toward a transport-link issue instead of the storage array.