failureThreshold: 3
```

## Cluster probe

### Cluster-writeable probe

The reply is '200 OK' if cluster has write quorum if not it returns '503 Service Unavailable'.

```
curl http://minio1:9001/minio/health/cluster
HTTP/1.1 503 Service Unavailable
Accept-Ranges: bytes
Content-Length: 0
Server: MinIO
Vary: Origin
X-Amz-Bucket-Region: us-east-1
X-Minio-Write-Quorum: 3
X-Amz-Request-Id: 16239D6AB80EBECF

			listenErrCallback(srv.Addrs[i], listenErrs[i])
		} else {
			interfaceFound = true
		}
	}
	if !interfaceFound {
		return nil, errors.New("no available interface found")
	}

	// Wrap given handler to do additional
	// * return 503 (service unavailable) if the server in shutdown.
	wrappedHandler := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		// If server is in shutdown.

		HTTPStatusCode: http.StatusBadRequest,
	},
	ErrBusy: {
		Code:           "ServerBusy",
		Description:    "The service is unavailable. Please retry.",
		HTTPStatusCode: http.StatusServiceUnavailable,
	},
	ErrUnauthorizedAccess: {
		Code:           "UnauthorizedAccess",
		Description:    "You are not authorized to perform this operation",

	"github.com/minio/minio/internal/kms"
)

const unavailable = "offline"

// ClusterCheckHandler returns if the server is ready for requests.
func ClusterCheckHandler(w http.ResponseWriter, r *http.Request) {
	ctx := newContext(r, w, "ClusterCheckHandler")

	objLayer := newObjectLayerFn()
	if objLayer == nil {
		w.Header().Set(xhttp.MinIOServerStatus, unavailable)
		writeResponse(w, http.StatusServiceUnavailable, nil, mimeNone)

						logger.Info("   - Drive: %s", disk.String())
					}
				})
				logger.Info(color.Yellow("WARNING:")+" Host %v has more than %v drives of set. "+
					"A host failure will result in data becoming unavailable.", host, wantAtMost)
			}
		}
	}

	// Save formats `format.json` across all disks.
	if err := saveFormatErasureAll(ctx, storageDisks, formats); err != nil {
		return nil, err
	}

)

const (
	memTotal     = "total"
	memUsed      = "used"
	memFree      = "free"
	memBuffers   = "buffers"
	memCache     = "cache"
	memUsedPerc  = "used_perc"
	memShared    = "shared"
	memAvailable = "available"
)

var (
	memTotalMD     = NewGaugeMD(memTotal, "Total memory on the node")
	memUsedMD      = NewGaugeMD(memUsed, "Used memory on the node")

type poolAvailableSpace struct {
	Index      int
	Available  uint64 // in bytes
	MaxUsedPct int    // Used disk percentage of most filled disk, rounded down.
}

// TotalAvailable - total available space
func (p serverPoolsAvailableSpace) TotalAvailable() uint64 {
	total := uint64(0)
	for _, z := range p {
		total += z.Available
	}
	return total
}

	"errors"
	"fmt"
	"io"
	"os"
	"path/filepath"
	"strconv"
	"strings"
	"syscall"

	"github.com/prometheus/procfs/blockdevice"
	"golang.org/x/sys/unix"
)

// GetInfo returns total and free bytes available in a directory, e.g. `/`.
func GetInfo(path string, firstTime bool) (info Info, err error) {
	s := syscall.Statfs_t{}
	err = syscall.Statfs(path, &s)
	if err != nil {
		return Info{}, err
	}

var errCrossDeviceLink = StorageErr("Rename across devices not allowed, please fix your backend configuration")

// errLessData - returned when less data available than what was requested.
var errLessData = StorageErr("less data available than what was requested")

// errMoreData = returned when more data was sent by the caller than what it was supposed to.

				[]string{"disk"}, nil),
			prometheus.GaugeValue,
			float64(disk.UsedSpace),
			disk.DrivePath,
		)

		// Total available space in the disk
		ch <- prometheus.MustNewConstMetric(
			prometheus.NewDesc(
				prometheus.BuildFQName(diskNamespace, "storage", "available"),
				"Total available space left on the drive",
				[]string{"disk"}, nil),
			prometheus.GaugeValue,
			float64(disk.AvailableSpace),