@Deprecated
  public static CharMatcher invisible() {
    return Invisible.INSTANCE;
  }

  /**
   * Determines whether a character is single-width (not double-width). When in doubt, this matcher
   * errs on the side of returning {@code false} (that is, it tends to assume a character is
   * double-width).
   *
   * <p><b>Note:</b> as the reference file evolves, we will modify this matcher to keep it up to
   * date.
   *

		rpcStats := rest.GetRPCStats()
		if globalIsDistErasure {
			metrics = append(metrics, MetricV2{
				Description: getInternodeFailedRequests(),
				Value:       float64(rpcStats.Errs),
			})
			metrics = append(metrics, MetricV2{
				Description: getInternodeTCPDialTimeout(),
				Value:       float64(rpcStats.DialErrs),
			})
			metrics = append(metrics, MetricV2{

		drivesCount    int
		expectedData   int
		expectedParity int
	}{
		{RRS, 16, 14, 2},
		{STANDARD, 16, 8, 8},
		{"", 16, 8, 8},
		{RRS, 16, 9, 7},
		{STANDARD, 16, 10, 6},
		{"", 16, 9, 7},
	}
	for i, tt := range tests {
		scfg := Config{
			Standard: StorageClass{
				Parity: 8,
			},
			RRS: StorageClass{
				Parity: 2,
			},
			initialized: true,
		}

// Config storage class configuration
type Config struct {
	Standard    StorageClass `json:"standard"`
	RRS         StorageClass `json:"rrs"`
	Optimize    string       `json:"optimize"`
	inlineBlock int64

	initialized bool
}

// UnmarshalJSON - Validate SS and RRS parity when unmarshalling JSON.
func (sCfg *Config) UnmarshalJSON(data []byte) error {
	type Alias Config
	aux := &struct {

	if len(cfg.Standard.String()) == 0 && len(cfg.RRS.String()) == 0 {
		// Do not enable storage-class if no settings found.
		return
	}
	s[config.StorageClassSubSys][config.Default] = config.KVS{
		config.KV{
			Key:   ClassStandard,
			Value: cfg.Standard.String(),
		},
		config.KV{
			Key:   ClassRRS,
			Value: cfg.RRS.String(),
		},
	}

	configStandardParityMD = NewGaugeMD(configStandardParity,
		"Standard storage class parity")
)

// loadClusterConfigMetrics - `MetricsLoaderFn` for cluster config
// such as standard and RRS parity.
func loadClusterConfigMetrics(ctx context.Context, m MetricValues, c *metricsCache) error {
	clusterDriveMetrics, err := c.clusterDriveMetrics.Get()
	if err != nil {
		metricsLogIf(ctx, err)
	} else {

		ignoreInUse, _ = strconv.ParseBool(forceStr)
	}

	// Disallow remote tiers with internal storage class names
	switch cfg.Name {
	case storageclass.STANDARD, storageclass.RRS:
		writeErrorResponseJSON(ctx, w, toAdminAPIErr(ctx, errTierReservedName), r.URL)
		return
	}

	// Refresh from the disk in case we had missed notifications about edits from peers.

	SyncEvents                  bool          `json:"sync_events"`
	ObjectMaxVersions           int64         `json:"object_max_versions"`
}

// UnmarshalJSON - Validate SS and RRS parity when unmarshalling JSON.
func (sCfg *Config) UnmarshalJSON(data []byte) error {
	type Alias Config
	aux := &struct {
		*Alias
	}{
		Alias: (*Alias)(sCfg),
	}
	return json.Unmarshal(data, &aux)
}

MINIO_STORAGE_CLASS_RRS: Format "EC:<Default_Parity_Reduced_Redundancy_Class>" (e.g. "EC:3"). This sets the number of parity drives for MinIO server in Reduced Redundancy mode. Objects are stored in Reduced Redundancy mode, if Put request specifies RRS storage class
Refer to the link https://github.com/minio/minio/tree/master/docs/erasure/storage-class for more information`,
	)

	ErrUnexpectedBackendVersion = newErrFn(
		"Backend version seems to be too recent",

```
KEY:
storage_class  define object level redundancy

ARGS:
standard  (string)    set the parity count for default standard storage class e.g. "EC:4"
rrs       (string)    set the parity count for reduced redundancy storage class e.g. "EC:2"
comment   (sentence)  optionally add a comment to this setting
```

or environment variables

```
KEY: