}

		op := auditTierOp{
			Tier:        tier,
			OutputBytes: bytes,
		}

		if err == nil {
			since := time.Since(startTime)
			op.TimeToResponseNS = since.Nanoseconds()
			globalTierMetrics.Observe(tier, since)
			globalTierMetrics.logSuccess(tier)
		} else {
			op.Error = err.Error()
			globalTierMetrics.logFailure(tier)
		}

		logger.GetReqInfo(ctx).AppendTags("tierStats", op)
	}
}

### What are the coding guidelines for MinIO?

         a0:31:fe:86:e3:8e:3f:49:af:6d:d5:ac:c7:c4:57:47:ce:97:
         7d:ab:b8:e9:75:ec:b4:39:fb:c8:cf:53:16:5b:1f:15:b6:7f:
         5a:d1:35:2d:fc:31:3a:10:e7:0c
```

> Observe the `Subject: CN = consoleAdmin` field.

Also, note that the certificate has to contain the `Extended Key Usage: TLS Web Client Authentication`. Otherwise, MinIO would not accept the certificate as client certificate.

func makeSubHandlerID(id HandlerID, subRoute string) subHandlerID {
	b := subHandlerID(sha256.Sum256([]byte(subRoute)))
	b[0] = byte(id)
	b[1] = 0 // Reserved
	return b
}

func (s subHandlerID) withHandler(id HandlerID) subHandlerID {
	s[0] = byte(id)
	s[1] = 0 // Reserved
	return s
}

func (s *subHandlerID) String() string {
	if s == nil {
		return ""
	}
	return hex.EncodeToString(s[:])
}

		readsKBPerSec:     "Kilobytes read per second on a drive",
		writesKBPerSec:    "Kilobytes written per second on a drive",
		readsAwait:        "Average time for read requests to be served on a drive",
		writesAwait:       "Average time for write requests to be served on a drive",
		percUtil:          "Percentage of time the disk was busy",
		usedBytes:         "Used bytes on a drive",
		totalBytes:        "Total bytes on a drive",

		}
	}
	return isMinioMetaBucket(bucketEntry) || isMinioReservedBucket(bucketEntry)
}

// Returns true if input bucket is a reserved minio meta bucket '.minio.sys'.
func isMinioMetaBucket(bucketName string) bool {
	return bucketName == minioMetaBucket
}

// Returns true if input bucket is a reserved minio bucket 'minio'.
func isMinioReservedBucket(bucketName string) bool {
	return bucketName == minioReservedBucket
}

At a high level metrics are grouped into three categories, listed in the following sub-sections. The path in each of the tables is relative to the top-level endpoint.

### Request metrics 

These are metrics about requests served by the (current) node.

| Path            | Description                                      |
|-----------------|--------------------------------------------------|

| `minio_node_drive_reads_await`       | Average time for read requests to be served on a drive.  |
| `minio_node_drive_writes_per_sec`    | Writes per second on a drive.                            |
| `minio_node_drive_writes_kb_per_sec` | Kilobytes written per second on a drive.                 |
| `minio_node_drive_writes_await`      | Average time for write requests to be served on a drive. |

//	anonReq   - unsigned *http.Request to invoke the handler's response for anonymous requests.
//	policyFunc    - function to return bucketPolicy statement which would permit the anonymous request to be served.
//
// The test works in 2 steps, here is the description of the steps.
//
//	STEP 1: Call the handler with the unsigned HTTP request (anonReq), assert for the `ErrAccessDenied` error response.

		// observations. This is to test the channel based
		// synchronization used internally.
		select {
		case <-ticker.C:
			ttfbHist.With(prometheus.Labels{"api": obs.label}).Observe(obs.val)
		}
	}

	metrics := getHistogramMetrics(ttfbHist, getBucketTTFBDistributionMD(), false)
	// additional labels for +Inf for all histogram metrics