Add data usage collect with its new admin API (#8553)

Admin data usage info API returns the following

(Only FS & XL, for now)

- Number of buckets
- Number of objects
- The total size of objects
- Objects histogram
- Bucket sizes

cmd/admin-handlers.go

@@ -290,6 +290,31 @@ func (a adminAPIHandlers) StorageInfoHandler(w http.ResponseWriter, r *http.Requ
 
 }
 
+// DataUsageInfoHandler - GET /minio/admin/v2/datausage
+// ----------
+// Get server/cluster data usage info
+func (a adminAPIHandlers) DataUsageInfoHandler(w http.ResponseWriter, r *http.Request) {
+	ctx := newContext(r, w, "DataUsageInfo")
+	objectAPI, _ := validateAdminReq(ctx, w, r, iampolicy.ListServerInfoAdminAction)
+	if objectAPI == nil {
+		return
+	}
+
+	dataUsageInfo, err := loadDataUsageFromBackend(ctx, objectAPI)
+	if err != nil {
+		writeErrorResponseJSON(ctx, w, errorCodes.ToAPIErr(ErrInternalError), r.URL)
+		return
+	}
+
+	dataUsageInfoJSON, err := json.Marshal(dataUsageInfo)
+	if err != nil {
+		writeErrorResponseJSON(ctx, w, errorCodes.ToAPIErr(ErrInternalError), r.URL)
+		return
+	}
+
+	writeSuccessResponseJSON(w, dataUsageInfoJSON)
+}
+
 // ServerCPULoadInfo holds informantion about cpu utilization
 // of one minio node. It also reports any errors if encountered
 // while trying to reach this server.

cmd/admin-heal-ops.go

@@ -587,6 +587,11 @@ func (h *healSequence) healItemsFromSourceCh() error {
 		logger.LogIf(h.ctx, err)
 	}
 
+	// Start healing the background ops prefix.
+	if err := h.healMinioSysMeta(backgroundOpsMetaPrefix)(); err != nil {
+		logger.LogIf(h.ctx, err)
+	}
+
 	for path := range h.sourceCh {
 
 		var itemType madmin.HealItemType
@@ -633,6 +638,11 @@ func (h *healSequence) healItems() error {
 		return err
 	}
 
+	// Start healing the background ops prefix.
+	if err := h.healMinioSysMeta(backgroundOpsMetaPrefix)(); err != nil {
+		logger.LogIf(h.ctx, err)
+	}
+
 	// Heal buckets and objects
 	return h.healBuckets()
 }

cmd/admin-router.go

@@ -53,6 +53,8 @@ func registerAdminRouter(router *mux.Router, enableConfigOps, enableIAMOps bool)
 
 	// StorageInfo operations
 	adminRouter.Methods(http.MethodGet).Path(adminAPIVersionPrefix + "/storageinfo").HandlerFunc(httpTraceAll(adminAPI.StorageInfoHandler))
+	// DataUsageInfo operations
+	adminRouter.Methods(http.MethodGet).Path(adminAPIVersionPrefix + "/datausageinfo").HandlerFunc(httpTraceAll(adminAPI.DataUsageInfoHandler))
 
 	if globalIsDistXL || globalIsXL {
 		/// Heal operations

cmd/data-usage.go

@@ -0,0 +1,142 @@
+/*
+ * MinIO Cloud Storage, (C) 2019 MinIO, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package cmd
+
+import (
+	"bytes"
+	"context"
+	"encoding/json"
+	"time"
+
+	"github.com/minio/minio/cmd/logger"
+	"github.com/minio/minio/pkg/hash"
+)
+
+const (
+	dataUsageObjName       = "data-usage"
+	dataUsageCrawlInterval = 12 * time.Hour
+)
+
+func initDataUsageStats() {
+	go runDataUsageInfoUpdateRoutine()
+}
+
+func runDataUsageInfoUpdateRoutine() {
+	// Wait until the object layer is ready
+	var objAPI ObjectLayer
+	for {
+		objAPI = newObjectLayerWithoutSafeModeFn()
+		if objAPI == nil {
+			time.Sleep(time.Second)
+			continue
+		}
+		break
+	}
+
+	ctx := context.Background()
+
+	switch v := objAPI.(type) {
+	case *xlZones:
+		runDataUsageInfoForXLZones(ctx, v, GlobalServiceDoneCh)
+	case *FSObjects:
+		runDataUsageInfoForFS(ctx, v, GlobalServiceDoneCh)
+	default:
+		return
+	}
+}
+
+func runDataUsageInfoForFS(ctx context.Context, fsObj *FSObjects, endCh <-chan struct{}) {
+	t := time.NewTicker(dataUsageCrawlInterval)
+	defer t.Stop()
+	for {
+		// Get data usage info of the FS Object
+		usageInfo := fsObj.crawlAndGetDataUsageInfo(ctx, endCh)
+		// Save the data usage in the disk
+		err := storeDataUsageInBackend(ctx, fsObj, usageInfo)
+		if err != nil {
+			logger.LogIf(ctx, err)
+		}
+		select {
+		case <-endCh:
+			return
+		// Wait until the next crawl interval
+		case <-t.C:
+		}
+	}
+}
+
+func runDataUsageInfoForXLZones(ctx context.Context, z *xlZones, endCh <-chan struct{}) {
+	locker := z.NewNSLock(ctx, minioMetaBucket, "leader-data-usage-info")
+	for {
+		err := locker.GetLock(newDynamicTimeout(time.Millisecond, time.Millisecond))
+		if err != nil {
+			time.Sleep(5 * time.Minute)
+			continue
+		}
+		// Break without locking
+		break
+	}
+
+	t := time.NewTicker(dataUsageCrawlInterval)
+	defer t.Stop()
+	for {
+		usageInfo := z.crawlAndGetDataUsage(ctx, endCh)
+		err := storeDataUsageInBackend(ctx, z, usageInfo)
+		if err != nil {
+			logger.LogIf(ctx, err)
+		}
+		select {
+		case <-endCh:
+			locker.Unlock()
+			return
+		case <-t.C:
+		}
+	}
+}
+
+func storeDataUsageInBackend(ctx context.Context, objAPI ObjectLayer, dataUsageInfo DataUsageInfo) error {
+	dataUsageJSON, err := json.Marshal(dataUsageInfo)
+	if err != nil {
+		return err
+	}
+
+	size := int64(len(dataUsageJSON))
+	r, err := hash.NewReader(bytes.NewReader(dataUsageJSON), size, "", "", size, false)
+	if err != nil {
+		return err
+	}
+
+	_, err = objAPI.PutObject(ctx, minioMetaBackgroundOpsBucket, dataUsageObjName, NewPutObjReader(r, nil, nil), ObjectOptions{})
+	return err
+}
+
+func loadDataUsageFromBackend(ctx context.Context, objAPI ObjectLayer) (DataUsageInfo, error) {
+	var dataUsageInfoJSON bytes.Buffer
+
+	err := objAPI.GetObject(ctx, minioMetaBackgroundOpsBucket, dataUsageObjName, 0, -1, &dataUsageInfoJSON, "", ObjectOptions{})
+	if err != nil {
+		return DataUsageInfo{}, nil
+	}
+
+	var dataUsageInfo DataUsageInfo
+	err = json.Unmarshal(dataUsageInfoJSON.Bytes(), &dataUsageInfo)
+	if err != nil {
+		return DataUsageInfo{}, err
+	}
+
+	return dataUsageInfo, nil
+}

cmd/fastwalk.go

@@ -0,0 +1,226 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// This code is imported from "golang.org/x/tools/internal/fastwalk",
+// only fastwalk.go is imported since we already implement readDir()
+// with some little tweaks.
+
+package cmd
+
+import (
+	"errors"
+	"os"
+	"path/filepath"
+	"runtime"
+	"strings"
+	"sync"
+)
+
+// ErrTraverseLink is used as a return value from WalkFuncs to indicate that the
+// symlink named in the call may be traversed.
+var ErrTraverseLink = errors.New("fastwalk: traverse symlink, assuming target is a directory")
+
+// ErrSkipFiles is a used as a return value from WalkFuncs to indicate that the
+// callback should not be called for any other files in the current directory.
+// Child directories will still be traversed.
+var ErrSkipFiles = errors.New("fastwalk: skip remaining files in directory")
+
+// Walk is a faster implementation of filepath.Walk.
+//
+// filepath.Walk's design necessarily calls os.Lstat on each file,
+// even if the caller needs less info.
+// Many tools need only the type of each file.
+// On some platforms, this information is provided directly by the readdir
+// system call, avoiding the need to stat each file individually.
+// fastwalk_unix.go contains a fork of the syscall routines.
+//
+// See golang.org/issue/16399
+//
+// Walk walks the file tree rooted at root, calling walkFn for
+// each file or directory in the tree, including root.
+//
+// If fastWalk returns filepath.SkipDir, the directory is skipped.
+//
+// Unlike filepath.Walk:
+//   * file stat calls must be done by the user.
+//     The only provided metadata is the file type, which does not include
+//     any permission bits.
+//   * multiple goroutines stat the filesystem concurrently. The provided
+//     walkFn must be safe for concurrent use.
+//   * fastWalk can follow symlinks if walkFn returns the TraverseLink
+//     sentinel error. It is the walkFn's responsibility to prevent
+//     fastWalk from going into symlink cycles.
+func fastWalk(root string, walkFn func(path string, typ os.FileMode) error) error {
+	// TODO(bradfitz): make numWorkers configurable? We used a
+	// minimum of 4 to give the kernel more info about multiple
+	// things we want, in hopes its I/O scheduling can take
+	// advantage of that. Hopefully most are in cache. Maybe 4 is
+	// even too low of a minimum. Profile more.
+	numWorkers := 4
+	if n := runtime.NumCPU(); n > numWorkers {
+		numWorkers = n
+	}
+
+	// Make sure to wait for all workers to finish, otherwise
+	// walkFn could still be called after returning. This Wait call
+	// runs after close(e.donec) below.
+	var wg sync.WaitGroup
+	defer wg.Wait()
+
+	w := &walker{
+		fn:       walkFn,
+		enqueuec: make(chan walkItem, numWorkers), // buffered for performance
+		workc:    make(chan walkItem, numWorkers), // buffered for performance
+		donec:    make(chan struct{}),
+
+		// buffered for correctness & not leaking goroutines:
+		resc: make(chan error, numWorkers),
+	}
+	defer close(w.donec)
+
+	for i := 0; i < numWorkers; i++ {
+		wg.Add(1)
+		go w.doWork(&wg)
+	}
+	todo := []walkItem{{dir: root}}
+	out := 0
+	for {
+		workc := w.workc
+		var workItem walkItem
+		if len(todo) == 0 {
+			workc = nil
+		} else {
+			workItem = todo[len(todo)-1]
+		}
+		select {
+		case workc <- workItem:
+			todo = todo[:len(todo)-1]
+			out++
+		case it := <-w.enqueuec:
+			todo = append(todo, it)
+		case err := <-w.resc:
+			out--
+			if err != nil {
+				return err
+			}
+			if out == 0 && len(todo) == 0 {
+				// It's safe to quit here, as long as the buffered
+				// enqueue channel isn't also readable, which might
+				// happen if the worker sends both another unit of
+				// work and its result before the other select was
+				// scheduled and both w.resc and w.enqueuec were
+				// readable.
+				select {
+				case it := <-w.enqueuec:
+					todo = append(todo, it)
+				default:
+					return nil
+				}
+			}
+		}
+	}
+}
+
+// doWork reads directories as instructed (via workc) and runs the
+// user's callback function.
+func (w *walker) doWork(wg *sync.WaitGroup) {
+	defer wg.Done()
+	for {
+		select {
+		case <-w.donec:
+			return
+		case it := <-w.workc:
+			select {
+			case <-w.donec:
+				return
+			case w.resc <- w.walk(it.dir, !it.callbackDone):
+			}
+		}
+	}
+}
+
+type walker struct {
+	fn func(path string, typ os.FileMode) error
+
+	donec    chan struct{} // closed on fastWalk's return
+	workc    chan walkItem // to workers
+	enqueuec chan walkItem // from workers
+	resc     chan error    // from workers
+}
+
+type walkItem struct {
+	dir          string
+	callbackDone bool // callback already called; don't do it again
+}
+
+func (w *walker) enqueue(it walkItem) {
+	select {
+	case w.enqueuec <- it:
+	case <-w.donec:
+	}
+}
+
+func (w *walker) onDirEnt(dirName, baseName string, typ os.FileMode) error {
+	joined := dirName + string(os.PathSeparator) + baseName
+	if typ == os.ModeDir {
+		w.enqueue(walkItem{dir: joined})
+		return nil
+	}
+
+	err := w.fn(joined, typ)
+	if typ == os.ModeSymlink {
+		if err == ErrTraverseLink {
+			// Set callbackDone so we don't call it twice for both the
+			// symlink-as-symlink and the symlink-as-directory later:
+			w.enqueue(walkItem{dir: joined, callbackDone: true})
+			return nil
+		}
+		if err == filepath.SkipDir {
+			// Permit SkipDir on symlinks too.
+			return nil
+		}
+	}
+	return err
+}
+
+func readDirFn(dirName string, fn func(dirName, entName string, typ os.FileMode) error) error {
+	fis, err := readDir(dirName)
+	if err != nil {
+		return err
+	}
+	skipFiles := false
+	for _, fi := range fis {
+		var mode os.FileMode
+		if strings.HasSuffix(fi, SlashSeparator) {
+			mode |= os.ModeDir
+		}
+
+		if mode == 0 && skipFiles {
+			continue
+		}
+
+		if err := fn(dirName, fi, mode); err != nil {
+			if err == ErrSkipFiles {
+				skipFiles = true
+				continue
+			}
+			return err
+		}
+	}
+	return nil
+}
+
+func (w *walker) walk(root string, runUserCallback bool) error {
+	if runUserCallback {
+		err := w.fn(root, os.ModeDir)
+		if err == filepath.SkipDir {
+			return nil
+		}
+		if err != nil {
+			return err
+		}
+	}
+
+	return readDirFn(root, w.onDirEnt)
+}

cmd/format-xl.go

@@ -771,6 +771,11 @@ func makeFormatXLMetaVolumes(disk StorageAPI) error {
 			return err
 		}
 	}
+	if err := disk.MakeVol(minioMetaBackgroundOpsBucket); err != nil {
+		if !IsErrIgnored(err, initMetaVolIgnoredErrs...) {
+			return err
+		}
+	}
 	if err := disk.MakeVol(minioMetaMultipartBucket); err != nil {
 		if !IsErrIgnored(err, initMetaVolIgnoredErrs...) {
 			return err

cmd/fs-v1.go

@@ -19,11 +19,13 @@ package cmd
 import (
 	"bytes"
 	"context"
+	"errors"
 	"io"
 	"io/ioutil"
 	"net/http"
 	"os"
 	"path"
+	"path/filepath"
 	"sort"
 	"strings"
 	"sync"
@@ -50,6 +52,11 @@ type FSObjects struct {
 	// Disk usage metrics
 	totalUsed uint64 // ref: https://golang.org/pkg/sync/atomic/#pkg-note-BUG
 
+	// The count of concurrent calls on FSObjects API
+	activeIOCount int64
+	// The active IO count ceiling for crawling to work
+	maxActiveIOCount int64
+
 	// Path to be exported over S3 API.
 	fsPath string
 	// meta json filename, varies by fs / cache backend.
@@ -100,6 +107,11 @@ func initMetaVolumeFS(fsPath, fsUUID string) error {
 		return err
 	}
 
+	metaStatsPath := pathJoin(fsPath, minioMetaBackgroundOpsBucket, fsUUID)
+	if err := os.MkdirAll(metaStatsPath, 0777); err != nil {
+		return err
+	}
+
 	metaMultipartPath := pathJoin(fsPath, minioMetaMultipartBucket)
 	return os.MkdirAll(metaMultipartPath, 0777)
 
@@ -147,6 +159,8 @@ func NewFSObjectLayer(fsPath string) (ObjectLayer, error) {
 		listPool:      NewTreeWalkPool(globalLookupTimeout),
 		appendFileMap: make(map[string]*fsAppendFile),
 		diskMount:     mountinfo.IsLikelyMountPoint(fsPath),
+
+		maxActiveIOCount: 10,
 	}
 
 	// Once the filesystem has initialized hold the read lock for
@@ -155,10 +169,6 @@ func NewFSObjectLayer(fsPath string) (ObjectLayer, error) {
 	// or cause changes on backend format.
 	fs.fsFormatRlk = rlk
 
-	if !fs.diskMount {
-		go fs.diskUsage(GlobalServiceDoneCh)
-	}
-
 	go fs.cleanupStaleMultipartUploads(ctx, GlobalMultipartCleanupInterval, GlobalMultipartExpiry, GlobalServiceDoneCh)
 
 	// Return successfully initialized object layer.
@@ -179,77 +189,14 @@ func (fs *FSObjects) Shutdown(ctx context.Context) error {
 	return fsRemoveAll(ctx, pathJoin(fs.fsPath, minioMetaTmpBucket, fs.fsUUID))
 }
 
-// diskUsage returns du information for the posix path, in a continuous routine.
-func (fs *FSObjects) diskUsage(doneCh chan struct{}) {
-	usageFn := func(ctx context.Context, entry string) error {
-		if httpServer := newHTTPServerFn(); httpServer != nil {
-			// Wait at max 1 minute for an inprogress request
-			// before proceeding to count the usage.
-			waitCount := 60
-			// Any requests in progress, delay the usage.
-			for httpServer.GetRequestCount() > 0 && waitCount > 0 {
-				waitCount--
-				time.Sleep(1 * time.Second)
-			}
-		}
-
-		select {
-		case <-doneCh:
-			return errWalkAbort
-		default:
-			fi, err := os.Stat(entry)
-			if err != nil {
-				err = osErrToFSFileErr(err)
-				return err
-			}
-			atomic.AddUint64(&fs.totalUsed, uint64(fi.Size()))
-		}
-		return nil
-	}
-
-	// Return this routine upon errWalkAbort, continue for any other error on purpose
-	// so that we can start the routine freshly in another 12 hours.
-	if err := getDiskUsage(context.Background(), fs.fsPath, usageFn); err == errWalkAbort {
-		return
-	}
-
-	for {
-		select {
-		case <-doneCh:
-			return
-		case <-time.After(globalUsageCheckInterval):
-			var usage uint64
-			usageFn = func(ctx context.Context, entry string) error {
-				if httpServer := newHTTPServerFn(); httpServer != nil {
-					// Wait at max 1 minute for an inprogress request
-					// before proceeding to count the usage.
-					waitCount := 60
-					// Any requests in progress, delay the usage.
-					for httpServer.GetRequestCount() > 0 && waitCount > 0 {
-						waitCount--
-						time.Sleep(1 * time.Second)
-					}
-				}
-
-				fi, err := os.Stat(entry)
-				if err != nil {
-					err = osErrToFSFileErr(err)
-					return err
-				}
-				usage = usage + uint64(fi.Size())
-				return nil
-			}
-
-			if err := getDiskUsage(context.Background(), fs.fsPath, usageFn); err != nil {
-				continue
-			}
-			atomic.StoreUint64(&fs.totalUsed, usage)
-		}
-	}
-}
-
 // StorageInfo - returns underlying storage statistics.
 func (fs *FSObjects) StorageInfo(ctx context.Context) StorageInfo {
+
+	atomic.AddInt64(&fs.activeIOCount, 1)
+	defer func() {
+		atomic.AddInt64(&fs.activeIOCount, -1)
+	}()
+
 	di, err := getDiskInfo(fs.fsPath)
 	if err != nil {
 		return StorageInfo{}
@@ -258,6 +205,7 @@ func (fs *FSObjects) StorageInfo(ctx context.Context) StorageInfo {
 	if !fs.diskMount {
 		used = atomic.LoadUint64(&fs.totalUsed)
 	}
+
 	storageInfo := StorageInfo{
 		Used:       []uint64{used},
 		Total:      []uint64{di.Total},
@@ -268,6 +216,98 @@ func (fs *FSObjects) StorageInfo(ctx context.Context) StorageInfo {
 	return storageInfo
 }
 
+func (fs *FSObjects) waitForLowActiveIO() error {
+	t := time.NewTicker(lowActiveIOWaitTick)
+	defer t.Stop()
+	for {
+		if atomic.LoadInt64(&fs.activeIOCount) >= fs.maxActiveIOCount {
+			select {
+			case <-GlobalServiceDoneCh:
+				return errors.New("forced exit")
+			case <-t.C:
+				continue
+			}
+		}
+		break
+	}
+
+	return nil
+
+}
+
+// crawlAndGetDataUsageInfo returns data usage stats of the current FS deployment
+func (fs *FSObjects) crawlAndGetDataUsageInfo(ctx context.Context, endCh <-chan struct{}) DataUsageInfo {
+
+	var dataUsageInfoMu sync.Mutex
+	var dataUsageInfo = DataUsageInfo{
+		BucketsSizes:          make(map[string]uint64),
+		ObjectsSizesHistogram: make(map[string]uint64),
+	}
+
+	walkFn := func(origPath string, typ os.FileMode) error {
+
+		select {
+		case <-GlobalServiceDoneCh:
+			return filepath.SkipDir
+		default:
+		}
+
+		if err := fs.waitForLowActiveIO(); err != nil {
+			return filepath.SkipDir
+		}
+
+		path := strings.TrimPrefix(origPath, fs.fsPath)
+		path = strings.TrimPrefix(path, SlashSeparator)
+
+		splits := splitN(path, SlashSeparator, 2)
+		bucket := splits[0]
+		prefix := splits[1]
+
+		if bucket == "" {
+			return nil
+		}
+
+		if isReservedOrInvalidBucket(bucket, false) {
+			return filepath.SkipDir
+		}
+
+		if prefix == "" {
+			dataUsageInfoMu.Lock()
+			dataUsageInfo.BucketsCount++
+			dataUsageInfo.BucketsSizes[bucket] = 0
+			dataUsageInfoMu.Unlock()
+			return nil
+		}
+
+		if typ&os.ModeDir != 0 {
+			return nil
+		}
+
+		// Get file size
+		fi, err := os.Stat(origPath)
+		if err != nil {
+			return nil
+		}
+		size := fi.Size()
+
+		dataUsageInfoMu.Lock()
+		dataUsageInfo.ObjectsCount++
+		dataUsageInfo.ObjectsTotalSize += uint64(size)
+		dataUsageInfo.BucketsSizes[bucket] += uint64(size)
+		dataUsageInfo.ObjectsSizesHistogram[objSizeToHistoInterval(uint64(size))]++
+		dataUsageInfoMu.Unlock()
+
+		return nil
+	}
+
+	fastWalk(fs.fsPath, walkFn)
+
+	dataUsageInfo.LastUpdate = UTCNow()
+	atomic.StoreUint64(&fs.totalUsed, dataUsageInfo.ObjectsTotalSize)
+
+	return dataUsageInfo
+}
+
 /// Bucket operations
 
 // getBucketDir - will convert incoming bucket names to
@@ -305,6 +345,12 @@ func (fs *FSObjects) MakeBucketWithLocation(ctx context.Context, bucket, locatio
 	if s3utils.CheckValidBucketNameStrict(bucket) != nil {
 		return BucketNameInvalid{Bucket: bucket}
 	}
+
+	atomic.AddInt64(&fs.activeIOCount, 1)
+	defer func() {
+		atomic.AddInt64(&fs.activeIOCount, -1)
+	}()
+
 	bucketDir, err := fs.getBucketDir(ctx, bucket)
 	if err != nil {
 		return toObjectErr(err, bucket)
@@ -324,6 +370,12 @@ func (fs *FSObjects) GetBucketInfo(ctx context.Context, bucket string) (bi Bucke
 		return bi, e
 	}
 	defer bucketLock.RUnlock()
+
+	atomic.AddInt64(&fs.activeIOCount, 1)
+	defer func() {
+		atomic.AddInt64(&fs.activeIOCount, -1)
+	}()
+
 	st, err := fs.statBucketDir(ctx, bucket)
 	if err != nil {
 		return bi, toObjectErr(err, bucket)
@@ -343,6 +395,12 @@ func (fs *FSObjects) ListBuckets(ctx context.Context) ([]BucketInfo, error) {
 		logger.LogIf(ctx, err)
 		return nil, err
 	}
+
+	atomic.AddInt64(&fs.activeIOCount, 1)
+	defer func() {
+		atomic.AddInt64(&fs.activeIOCount, -1)
+	}()
+
 	var bucketInfos []BucketInfo
 	entries, err := readDir((fs.fsPath))
 	if err != nil {
@@ -388,6 +446,12 @@ func (fs *FSObjects) DeleteBucket(ctx context.Context, bucket string) error {
 		return err
 	}
 	defer bucketLock.Unlock()
+
+	atomic.AddInt64(&fs.activeIOCount, 1)
+	defer func() {
+		atomic.AddInt64(&fs.activeIOCount, -1)
+	}()
+
 	bucketDir, err := fs.getBucketDir(ctx, bucket)
 	if err != nil {
 		return toObjectErr(err, bucket)
@@ -425,6 +489,11 @@ func (fs *FSObjects) CopyObject(ctx context.Context, srcBucket, srcObject, dstBu
 		defer objectDWLock.Unlock()
 	}
 
+	atomic.AddInt64(&fs.activeIOCount, 1)
+	defer func() {
+		atomic.AddInt64(&fs.activeIOCount, -1)
+	}()
+
 	if _, err := fs.statBucketDir(ctx, srcBucket); err != nil {
 		return oi, toObjectErr(err, srcBucket)
 	}
@@ -482,6 +551,11 @@ func (fs *FSObjects) GetObjectNInfo(ctx context.Context, bucket, object string,
 		return nil, err
 	}
 
+	atomic.AddInt64(&fs.activeIOCount, 1)
+	defer func() {
+		atomic.AddInt64(&fs.activeIOCount, -1)
+	}()
+
 	if _, err = fs.statBucketDir(ctx, bucket); err != nil {
 		return nil, toObjectErr(err, bucket)
 	}
@@ -583,6 +657,12 @@ func (fs *FSObjects) GetObject(ctx context.Context, bucket, object string, offse
 		return err
 	}
 	defer objectLock.RUnlock()
+
+	atomic.AddInt64(&fs.activeIOCount, 1)
+	defer func() {
+		atomic.AddInt64(&fs.activeIOCount, -1)
+	}()
+
 	return fs.getObject(ctx, bucket, object, offset, length, writer, etag, true)
 }
 
@@ -768,6 +848,12 @@ func (fs *FSObjects) getObjectInfoWithLock(ctx context.Context, bucket, object s
 
 // GetObjectInfo - reads object metadata and replies back ObjectInfo.
 func (fs *FSObjects) GetObjectInfo(ctx context.Context, bucket, object string, opts ObjectOptions) (oi ObjectInfo, e error) {
+
+	atomic.AddInt64(&fs.activeIOCount, 1)
+	defer func() {
+		atomic.AddInt64(&fs.activeIOCount, -1)
+	}()
+
 	oi, err := fs.getObjectInfoWithLock(ctx, bucket, object)
 	if err == errCorruptedFormat || err == io.EOF {
 		objectLock := fs.NewNSLock(ctx, bucket, object)
@@ -823,6 +909,11 @@ func (fs *FSObjects) PutObject(ctx context.Context, bucket string, object string
 	}
 	defer objectLock.Unlock()
 
+	atomic.AddInt64(&fs.activeIOCount, 1)
+	defer func() {
+		atomic.AddInt64(&fs.activeIOCount, -1)
+	}()
+
 	return fs.putObject(ctx, bucket, object, r, opts)
 }
 
@@ -981,6 +1072,11 @@ func (fs *FSObjects) DeleteObject(ctx context.Context, bucket, object string) er
 		return err
 	}
 
+	atomic.AddInt64(&fs.activeIOCount, 1)
+	defer func() {
+		atomic.AddInt64(&fs.activeIOCount, -1)
+	}()
+
 	if _, err := fs.statBucketDir(ctx, bucket); err != nil {
 		return toObjectErr(err, bucket)
 	}
@@ -1119,6 +1215,12 @@ func (fs *FSObjects) getObjectETag(ctx context.Context, bucket, entry string, lo
 // ListObjects - list all objects at prefix upto maxKeys., optionally delimited by '/'. Maintains the list pool
 // state for future re-entrant list requests.
 func (fs *FSObjects) ListObjects(ctx context.Context, bucket, prefix, marker, delimiter string, maxKeys int) (loi ListObjectsInfo, e error) {
+
+	atomic.AddInt64(&fs.activeIOCount, 1)
+	defer func() {
+		atomic.AddInt64(&fs.activeIOCount, -1)
+	}()
+
 	return listObjects(ctx, fs, bucket, prefix, marker, delimiter, maxKeys, fs.listPool,
 		fs.listDirFactory(), fs.getObjectInfo, fs.getObjectInfo)
 }

cmd/naughty-disk_test.go

@@ -80,6 +80,10 @@ func (d *naughtyDisk) calcError() (err error) {
 func (d *naughtyDisk) SetDiskID(id string) {
 }
 
+func (d *naughtyDisk) CrawlAndGetDataUsage(endCh <-chan struct{}) (info DataUsageInfo, err error) {
+	return d.disk.CrawlAndGetDataUsage(endCh)
+}
+
 func (d *naughtyDisk) DiskInfo() (info DiskInfo, err error) {
 	if err := d.calcError(); err != nil {
 		return info, err

cmd/object-api-common.go

@@ -450,3 +450,26 @@ func listObjects(ctx context.Context, obj ObjectLayer, bucket, prefix, marker, d
 	// Success.
 	return result, nil
 }
+
+// Fetch the histogram interval corresponding
+// to the passed object size.
+func objSizeToHistoInterval(usize uint64) string {
+	size := int64(usize)
+
+	var interval objectHistogramInterval
+	for _, interval = range ObjectsHistogramIntervals {
+		var cond1, cond2 bool
+		if size >= interval.start || interval.start == -1 {
+			cond1 = true
+		}
+		if size <= interval.end || interval.end == -1 {
+			cond2 = true
+		}
+		if cond1 && cond2 {
+			return interval.name
+		}
+	}
+
+	// This would be the last element of histogram intervals
+	return interval.name
+}

cmd/object-api-datatypes.go

@@ -70,6 +70,39 @@ type StorageInfo struct {
 	}
 }
 
+// objectHistogramInterval is an interval that will be
+// used to report the histogram of objects data sizes
+type objectHistogramInterval struct {
+	name       string
+	start, end int64
+}
+
+// ObjectsHistogramIntervals is the list of all intervals
+// of object sizes to be included in objects histogram.
+var ObjectsHistogramIntervals = []objectHistogramInterval{
+	{"LESS_THAN_1024_B", -1, 1024 - 1},
+	{"BETWEEN_1024_B_AND_1_MB", 1024, 1024*1024 - 1},
+	{"BETWEEN_1_MB_AND_10_MB", 1024 * 1024, 1024*1024*10 - 1},
+	{"BETWEEN_10_MB_AND_64_MB", 1024 * 1024 * 10, 1024*1024*64 - 1},
+	{"BETWEEN_64_MB_AND_128_MB", 1024 * 1024 * 64, 1024*1024*128 - 1},
+	{"BETWEEN_128_MB_AND_512_MB", 1024 * 1024 * 128, 1024*1024*512 - 1},
+	{"GREATER_THAN_512_MB", 1024 * 1024 * 512, -1},
+}
+
+// DataUsageInfo represents data usage stats of the underlying Object API
+type DataUsageInfo struct {
+	// The timestamp of when the data usage info is generated
+	LastUpdate time.Time `json:"lastUpdate"`
+
+	ObjectsCount uint64 `json:"objectsCount"`
+	// Objects total size
+	ObjectsTotalSize      uint64            `json:"objectsTotalSize"`
+	ObjectsSizesHistogram map[string]uint64 `json:"objectsSizesHistogram"`
+
+	BucketsCount uint64            `json:"bucketsCount"`
+	BucketsSizes map[string]uint64 `json:"bucketsSizes"`
+}
+
 // BucketInfo - represents bucket metadata.
 type BucketInfo struct {
 	// Name of the bucket.

cmd/object-api-utils.go

@@ -51,6 +51,10 @@ import (
 const (
 	// MinIO meta bucket.
 	minioMetaBucket = ".minio.sys"
+	// Background ops meta prefix
+	backgroundOpsMetaPrefix = "background-ops"
+	// MinIO Stats meta prefix.
+	minioMetaBackgroundOpsBucket = minioMetaBucket + SlashSeparator + backgroundOpsMetaPrefix
 	// Multipart meta prefix.
 	mpartMetaPrefix = "multipart"
 	// MinIO Multipart meta prefix.
@@ -72,7 +76,8 @@ const (
 func isMinioMetaBucketName(bucket string) bool {
 	return bucket == minioMetaBucket ||
 		bucket == minioMetaMultipartBucket ||
-		bucket == minioMetaTmpBucket
+		bucket == minioMetaTmpBucket ||
+		bucket == minioMetaBackgroundOpsBucket
 }
 
 // IsValidBucketName verifies that a bucket name is in accordance with

cmd/posix-diskid-check.go

@@ -38,6 +38,10 @@ func (p *posixDiskIDCheck) IsOnline() bool {
 	return storedDiskID == p.diskID
 }
 
+func (p *posixDiskIDCheck) CrawlAndGetDataUsage(endCh <-chan struct{}) (DataUsageInfo, error) {
+	return p.storage.CrawlAndGetDataUsage(endCh)
+}
+
 func (p *posixDiskIDCheck) LastError() error {
 	return p.storage.LastError()
 }

cmd/posix.go

@@ -59,6 +59,10 @@ const (
 	readAheadBuffers = 4
 	// Size of each buffer.
 	readAheadBufSize = 1 << 20
+
+	// Wait interval to check if active IO count is low
+	// to proceed crawling to compute data usage
+	lowActiveIOWaitTick = 100 * time.Millisecond
 )
 
 // isValidVolname verifies a volname name in accordance with object
@@ -82,6 +86,9 @@ type posix struct {
 	totalUsed  uint64 // ref: https://golang.org/pkg/sync/atomic/#pkg-note-BUG
 	ioErrCount int32  // ref: https://golang.org/pkg/sync/atomic/#pkg-note-BUG
 
+	activeIOCount    int32
+	maxActiveIOCount int32
+
 	diskPath string
 	pool     sync.Pool
 
@@ -212,12 +219,9 @@ func newPosix(path string) (*posix, error) {
 				return &b
 			},
 		},
-		stopUsageCh: make(chan struct{}),
+		stopUsageCh:      make(chan struct{}),
-		diskMount:   mountinfo.IsLikelyMountPoint(path),
+		diskMount:        mountinfo.IsLikelyMountPoint(path),
-	}
+		maxActiveIOCount: 10,
-
-	if !p.diskMount {
-		go p.diskUsage(GlobalServiceDoneCh)
 	}
 
 	// Success.
@@ -321,6 +325,105 @@ func (s *posix) IsOnline() bool {
 	return true
 }
 
+func isQuitting(endCh chan struct{}) bool {
+	select {
+	case <-endCh:
+		return true
+	default:
+		return false
+	}
+}
+
+func (s *posix) waitForLowActiveIO() error {
+	t := time.NewTicker(lowActiveIOWaitTick)
+	defer t.Stop()
+	for {
+		if atomic.LoadInt32(&s.activeIOCount) >= s.maxActiveIOCount {
+			select {
+			case <-GlobalServiceDoneCh:
+				return errors.New("forced exit")
+			case <-t.C:
+				continue
+			}
+		}
+		break
+	}
+	return nil
+}
+
+func (s *posix) CrawlAndGetDataUsage(endCh <-chan struct{}) (DataUsageInfo, error) {
+
+	var dataUsageInfoMu sync.Mutex
+	var dataUsageInfo = DataUsageInfo{
+		BucketsSizes:          make(map[string]uint64),
+		ObjectsSizesHistogram: make(map[string]uint64),
+	}
+
+	walkFn := func(origPath string, typ os.FileMode) error {
+
+		select {
+		case <-GlobalServiceDoneCh:
+			return filepath.SkipDir
+		default:
+		}
+
+		if err := s.waitForLowActiveIO(); err != nil {
+			return filepath.SkipDir
+		}
+
+		path := strings.TrimPrefix(origPath, s.diskPath)
+		path = strings.TrimPrefix(path, SlashSeparator)
+
+		splits := splitN(path, SlashSeparator, 2)
+
+		bucket := splits[0]
+		prefix := splits[1]
+
+		if bucket == "" {
+			return nil
+		}
+
+		if isReservedOrInvalidBucket(bucket, false) {
+			return nil
+		}
+
+		if prefix == "" {
+			dataUsageInfoMu.Lock()
+			dataUsageInfo.BucketsCount++
+			dataUsageInfo.BucketsSizes[bucket] = 0
+			dataUsageInfoMu.Unlock()
+			return nil
+		}
+
+		if strings.HasSuffix(prefix, "/xl.json") {
+			xlMetaBuf, err := ioutil.ReadFile(origPath)
+			if err != nil {
+				return nil
+			}
+			meta, err := xlMetaV1UnmarshalJSON(context.Background(), xlMetaBuf)
+			if err != nil {
+				return nil
+			}
+
+			dataUsageInfoMu.Lock()
+			dataUsageInfo.ObjectsCount++
+			dataUsageInfo.ObjectsTotalSize += uint64(meta.Stat.Size)
+			dataUsageInfo.BucketsSizes[bucket] += uint64(meta.Stat.Size)
+			dataUsageInfo.ObjectsSizesHistogram[objSizeToHistoInterval(uint64(meta.Stat.Size))]++
+			dataUsageInfoMu.Unlock()
+		}
+
+		return nil
+	}
+
+	fastWalk(s.diskPath, walkFn)
+
+	dataUsageInfo.LastUpdate = UTCNow()
+
+	atomic.StoreUint64(&s.totalUsed, dataUsageInfo.ObjectsTotalSize)
+	return dataUsageInfo, nil
+}
+
 // DiskInfo is an extended type which returns current
 // disk usage per path.
 type DiskInfo struct {
@@ -348,6 +451,11 @@ func (s *posix) DiskInfo() (info DiskInfo, err error) {
 		return info, errFaultyDisk
 	}
 
+	atomic.AddInt32(&s.activeIOCount, 1)
+	defer func() {
+		atomic.AddInt32(&s.activeIOCount, -1)
+	}()
+
 	di, err := getDiskInfo(s.diskPath)
 	if err != nil {
 		return info, err
@@ -437,88 +545,6 @@ func (s *posix) getDiskID() (string, error) {
 	return s.diskID, nil
 }
 
-// diskUsage returns du information for the posix path, in a continuous routine.
-func (s *posix) diskUsage(doneCh chan struct{}) {
-	ticker := time.NewTicker(globalUsageCheckInterval)
-	defer ticker.Stop()
-
-	usageFn := func(ctx context.Context, entry string) error {
-		if httpServer := newHTTPServerFn(); httpServer != nil {
-			// Wait at max 1 minute for an inprogress request
-			// before proceeding to count the usage.
-			waitCount := 60
-			// Any requests in progress, delay the usage.
-			for httpServer.GetRequestCount() > 0 && waitCount > 0 {
-				waitCount--
-				time.Sleep(1 * time.Second)
-			}
-		}
-
-		select {
-		case <-doneCh:
-			return errWalkAbort
-		case <-s.stopUsageCh:
-			return errWalkAbort
-		default:
-			fi, err := os.Stat(entry)
-			if err != nil {
-				err = osErrToFSFileErr(err)
-				return err
-			}
-			atomic.AddUint64(&s.totalUsed, uint64(fi.Size()))
-			return nil
-		}
-	}
-
-	// Return this routine upon errWalkAbort, continue for any other error on purpose
-	// so that we can start the routine freshly in another 12 hours.
-	if err := getDiskUsage(context.Background(), s.diskPath, usageFn); err == errWalkAbort {
-		return
-	}
-
-	for {
-		select {
-		case <-s.stopUsageCh:
-			return
-		case <-doneCh:
-			return
-		case <-time.After(globalUsageCheckInterval):
-			var usage uint64
-			usageFn = func(ctx context.Context, entry string) error {
-				if httpServer := newHTTPServerFn(); httpServer != nil {
-					// Wait at max 1 minute for an inprogress request
-					// before proceeding to count the usage.
-					waitCount := 60
-					// Any requests in progress, delay the usage.
-					for httpServer.GetRequestCount() > 0 && waitCount > 0 {
-						waitCount--
-						time.Sleep(1 * time.Second)
-					}
-				}
-
-				select {
-				case <-s.stopUsageCh:
-					return errWalkAbort
-				default:
-					fi, err := os.Stat(entry)
-					if err != nil {
-						err = osErrToFSFileErr(err)
-						return err
-					}
-					usage = usage + uint64(fi.Size())
-					return nil
-				}
-			}
-
-			if err := getDiskUsage(context.Background(), s.diskPath, usageFn); err != nil {
-				continue
-			}
-
-			atomic.StoreUint64(&s.totalUsed, usage)
-		}
-	}
-}
-
 // Make a volume entry.
 func (s *posix) SetDiskID(id string) {
 	// NO-OP for posix as it is handled either by posixDiskIDCheck{} for local disks or
@@ -541,6 +567,11 @@ func (s *posix) MakeVol(volume string) (err error) {
 		return errInvalidArgument
 	}
 
+	atomic.AddInt32(&s.activeIOCount, 1)
+	defer func() {
+		atomic.AddInt32(&s.activeIOCount, -1)
+	}()
+
 	volumeDir, err := s.getVolDir(volume)
 	if err != nil {
 		return err
@@ -576,6 +607,11 @@ func (s *posix) ListVols() (volsInfo []VolInfo, err error) {
 		return nil, errFaultyDisk
 	}
 
+	atomic.AddInt32(&s.activeIOCount, 1)
+	defer func() {
+		atomic.AddInt32(&s.activeIOCount, -1)
+	}()
+
 	volsInfo, err = listVols(s.diskPath)
 	if err != nil {
 		if isSysErrIO(err) {
@@ -641,6 +677,11 @@ func (s *posix) StatVol(volume string) (volInfo VolInfo, err error) {
 		return VolInfo{}, errFaultyDisk
 	}
 
+	atomic.AddInt32(&s.activeIOCount, 1)
+	defer func() {
+		atomic.AddInt32(&s.activeIOCount, -1)
+	}()
+
 	// Verify if volume is valid and it exists.
 	volumeDir, err := s.getVolDir(volume)
 	if err != nil {
@@ -678,6 +719,11 @@ func (s *posix) DeleteVol(volume string) (err error) {
 		return errFaultyDisk
 	}
 
+	atomic.AddInt32(&s.activeIOCount, 1)
+	defer func() {
+		atomic.AddInt32(&s.activeIOCount, -1)
+	}()
+
 	// Verify if volume is valid and it exists.
 	volumeDir, err := s.getVolDir(volume)
 	if err != nil {
@@ -716,6 +762,11 @@ func (s *posix) Walk(volume, dirPath, marker string, recursive bool, leafFile st
 		return nil, errFaultyDisk
 	}
 
+	atomic.AddInt32(&s.activeIOCount, 1)
+	defer func() {
+		atomic.AddInt32(&s.activeIOCount, -1)
+	}()
+
 	// Verify if volume is valid and it exists.
 	volumeDir, err := s.getVolDir(volume)
 	if err != nil {
@@ -789,6 +840,11 @@ func (s *posix) ListDir(volume, dirPath string, count int, leafFile string) (ent
 		return nil, errFaultyDisk
 	}
 
+	atomic.AddInt32(&s.activeIOCount, 1)
+	defer func() {
+		atomic.AddInt32(&s.activeIOCount, -1)
+	}()
+
 	// Verify if volume is valid and it exists.
 	volumeDir, err := s.getVolDir(volume)
 	if err != nil {
@@ -841,6 +897,11 @@ func (s *posix) ReadAll(volume, path string) (buf []byte, err error) {
 		return nil, errFaultyDisk
 	}
 
+	atomic.AddInt32(&s.activeIOCount, 1)
+	defer func() {
+		atomic.AddInt32(&s.activeIOCount, -1)
+	}()
+
 	volumeDir, err := s.getVolDir(volume)
 	if err != nil {
 		return nil, err
@@ -914,6 +975,11 @@ func (s *posix) ReadFile(volume, path string, offset int64, buffer []byte, verif
 		return 0, errFaultyDisk
 	}
 
+	atomic.AddInt32(&s.activeIOCount, 1)
+	defer func() {
+		atomic.AddInt32(&s.activeIOCount, -1)
+	}()
+
 	volumeDir, err := s.getVolDir(volume)
 	if err != nil {
 		return 0, err
@@ -1082,6 +1148,11 @@ func (s *posix) ReadFileStream(volume, path string, offset, length int64) (io.Re
 		return nil, errFaultyDisk
 	}
 
+	atomic.AddInt32(&s.activeIOCount, 1)
+	defer func() {
+		atomic.AddInt32(&s.activeIOCount, -1)
+	}()
+
 	volumeDir, err := s.getVolDir(volume)
 	if err != nil {
 		return nil, err
@@ -1165,6 +1236,11 @@ func (s *posix) CreateFile(volume, path string, fileSize int64, r io.Reader) (er
 		return errFaultyDisk
 	}
 
+	atomic.AddInt32(&s.activeIOCount, 1)
+	defer func() {
+		atomic.AddInt32(&s.activeIOCount, -1)
+	}()
+
 	// Validate if disk is indeed free.
 	if err = checkDiskFree(s.diskPath, fileSize); err != nil {
 		if isSysErrIO(err) {
@@ -1264,6 +1340,11 @@ func (s *posix) WriteAll(volume, path string, reader io.Reader) (err error) {
 		return errFaultyDisk
 	}
 
+	atomic.AddInt32(&s.activeIOCount, 1)
+	defer func() {
+		atomic.AddInt32(&s.activeIOCount, -1)
+	}()
+
 	// Create file if not found. Note that it is created with os.O_EXCL flag as the file
 	// always is supposed to be created in the tmp directory with a unique file name.
 	w, err := s.openFile(volume, path, os.O_CREATE|os.O_SYNC|os.O_WRONLY|os.O_EXCL)
@@ -1293,6 +1374,11 @@ func (s *posix) AppendFile(volume, path string, buf []byte) (err error) {
 		return errFaultyDisk
 	}
 
+	atomic.AddInt32(&s.activeIOCount, 1)
+	defer func() {
+		atomic.AddInt32(&s.activeIOCount, -1)
+	}()
+
 	var w *os.File
 	// Create file if not found. Not doing O_DIRECT here to avoid the code that does buffer aligned writes.
 	// AppendFile() is only used by healing code to heal objects written in old format.
@@ -1320,6 +1406,11 @@ func (s *posix) StatFile(volume, path string) (file FileInfo, err error) {
 		return FileInfo{}, errFaultyDisk
 	}
 
+	atomic.AddInt32(&s.activeIOCount, 1)
+	defer func() {
+		atomic.AddInt32(&s.activeIOCount, -1)
+	}()
+
 	volumeDir, err := s.getVolDir(volume)
 	if err != nil {
 		return FileInfo{}, err
@@ -1416,6 +1507,11 @@ func (s *posix) DeleteFile(volume, path string) (err error) {
 		return errFaultyDisk
 	}
 
+	atomic.AddInt32(&s.activeIOCount, 1)
+	defer func() {
+		atomic.AddInt32(&s.activeIOCount, -1)
+	}()
+
 	volumeDir, err := s.getVolDir(volume)
 	if err != nil {
 		return err
@@ -1465,6 +1561,11 @@ func (s *posix) RenameFile(srcVolume, srcPath, dstVolume, dstPath string) (err e
 		return errFaultyDisk
 	}
 
+	atomic.AddInt32(&s.activeIOCount, 1)
+	defer func() {
+		atomic.AddInt32(&s.activeIOCount, -1)
+	}()
+
 	srcVolumeDir, err := s.getVolDir(srcVolume)
 	if err != nil {
 		return err
@@ -1557,6 +1658,11 @@ func (s *posix) VerifyFile(volume, path string, fileSize int64, algo BitrotAlgor
 		return errFaultyDisk
 	}
 
+	atomic.AddInt32(&s.activeIOCount, 1)
+	defer func() {
+		atomic.AddInt32(&s.activeIOCount, -1)
+	}()
+
 	volumeDir, err := s.getVolDir(volume)
 	if err != nil {
 		return err

cmd/prepare-storage.go

@@ -223,6 +223,12 @@ func connectLoadInitFormats(retryCount int, firstDisk bool, endpoints Endpoints,
 		// Assign globalDeploymentID on first run for the
 		// minio server managing the first disk
 		globalDeploymentID = format.ID
+	} else {
+		// The first will always recreate some directories inside .minio.sys
+		// such as, tmp, multipart and background-ops
+		if firstDisk {
+			initFormatXLMetaVolume(storageDisks, formatConfigs)
+		}
 	}
 
 	// Return error when quorum unformatted disks - indicating we are

cmd/server-main.go

@@ -437,6 +437,7 @@ func serverMain(ctx *cli.Context) {
 		globalObjLayerMutex.Unlock()
 	}
 
+	initDataUsageStats()
 	initDailyLifecycle()
 
 	if globalIsXL {

cmd/storage-interface.go

@@ -32,6 +32,7 @@ type StorageAPI interface {
 	SetDiskID(id string)
 
 	DiskInfo() (info DiskInfo, err error)
+	CrawlAndGetDataUsage(endCh <-chan struct{}) (DataUsageInfo, error)
 
 	// Volume operations.
 	MakeVol(volume string) (err error)

cmd/storage-rest-client.go

@@ -147,6 +147,28 @@ func (client *storageRESTClient) IsOnline() bool {
 	return atomic.LoadInt32(&client.connected) == 1
 }
 
+func (client *storageRESTClient) CrawlAndGetDataUsage(endCh <-chan struct{}) (DataUsageInfo, error) {
+	respBody, err := client.call(storageRESTMethodCrawlAndGetDataUsage, nil, nil, -1)
+	defer http.DrainBody(respBody)
+	if err != nil {
+		return DataUsageInfo{}, err
+	}
+	reader := bufio.NewReader(respBody)
+	for {
+		b, err := reader.ReadByte()
+		if err != nil {
+			return DataUsageInfo{}, err
+		}
+		if b != ' ' {
+			reader.UnreadByte()
+			break
+		}
+	}
+	var usageInfo DataUsageInfo
+	err = gob.NewDecoder(reader).Decode(&usageInfo)
+	return usageInfo, err
+}
+
 // LastError - returns the network error if any.
 func (client *storageRESTClient) LastError() error {
 	return client.lastError

cmd/storage-rest-common.go

@@ -17,17 +17,18 @@
 package cmd
 
 const (
-	storageRESTVersion       = "v10"
+	storageRESTVersion       = "v11"
-	storageRESTVersionPrefix = SlashSeparator + "v10"
+	storageRESTVersionPrefix = SlashSeparator + storageRESTVersion
 	storageRESTPrefix        = minioReservedBucketPath + "/storage"
 )
 
 const (
-	storageRESTMethodDiskInfo  = "/diskinfo"
+	storageRESTMethodDiskInfo             = "/diskinfo"
-	storageRESTMethodMakeVol   = "/makevol"
+	storageRESTMethodCrawlAndGetDataUsage = "/crawlandgetdatausage"
-	storageRESTMethodStatVol   = "/statvol"
+	storageRESTMethodMakeVol              = "/makevol"
-	storageRESTMethodDeleteVol = "/deletevol"
+	storageRESTMethodStatVol              = "/statvol"
-	storageRESTMethodListVols  = "/listvols"
+	storageRESTMethodDeleteVol            = "/deletevol"
+	storageRESTMethodListVols             = "/listvols"
 
 	storageRESTMethodAppendFile     = "/appendfile"
 	storageRESTMethodCreateFile     = "/createfile"

cmd/storage-rest-server.go

@@ -112,6 +112,31 @@ func (s *storageRESTServer) DiskInfoHandler(w http.ResponseWriter, r *http.Reque
 	gob.NewEncoder(w).Encode(info)
 }
 
+func (s *storageRESTServer) CrawlAndGetDataUsageHandler(w http.ResponseWriter, r *http.Request) {
+	if !s.IsValid(w, r) {
+		return
+	}
+
+	usageInfo, err := s.storage.CrawlAndGetDataUsage(GlobalServiceDoneCh)
+	if err != nil {
+		s.writeErrorResponse(w, err)
+		return
+	}
+
+	w.Header().Set(xhttp.ContentType, "text/event-stream")
+	doneCh := sendWhiteSpaceToHTTPResponse(w)
+	usageInfo, err = s.storage.CrawlAndGetDataUsage(GlobalServiceDoneCh)
+	<-doneCh
+
+	if err != nil {
+		s.writeErrorResponse(w, err)
+		return
+	}
+
+	gob.NewEncoder(w).Encode(usageInfo)
+	w.(http.Flusher).Flush()
+}
+
 // MakeVolHandler - make a volume.
 func (s *storageRESTServer) MakeVolHandler(w http.ResponseWriter, r *http.Request) {
 	if !s.IsValid(w, r) {
@@ -489,8 +514,9 @@ func (s *storageRESTServer) RenameFileHandler(w http.ResponseWriter, r *http.Req
 	}
 }
 
-// Send whitespace to the client to avoid timeouts as bitrot verification can take time on spinning/slow disks.
+// Send whitespace to the client to avoid timeouts with long storage
-func sendWhiteSpaceVerifyFile(w http.ResponseWriter) <-chan struct{} {
+// operations, such as bitrot verification or data usage crawling.
+func sendWhiteSpaceToHTTPResponse(w http.ResponseWriter) <-chan struct{} {
 	doneCh := make(chan struct{})
 	go func() {
 		ticker := time.NewTicker(time.Second * 10)
@@ -548,7 +574,7 @@ func (s *storageRESTServer) VerifyFile(w http.ResponseWriter, r *http.Request) {
 	}
 	w.Header().Set(xhttp.ContentType, "text/event-stream")
 	encoder := gob.NewEncoder(w)
-	doneCh := sendWhiteSpaceVerifyFile(w)
+	doneCh := sendWhiteSpaceToHTTPResponse(w)
 	err = s.storage.VerifyFile(volume, filePath, size, BitrotAlgorithmFromString(algoStr), hash, int64(shardSize))
 	<-doneCh
 	vresp := &VerifyFileResp{}
@@ -577,6 +603,7 @@ func registerStorageRESTHandlers(router *mux.Router, endpointZones EndpointZones
 			subrouter := router.PathPrefix(path.Join(storageRESTPrefix, endpoint.Path)).Subrouter()
 
 			subrouter.Methods(http.MethodPost).Path(storageRESTVersionPrefix + storageRESTMethodDiskInfo).HandlerFunc(httpTraceHdrs(server.DiskInfoHandler))
+			subrouter.Methods(http.MethodPost).Path(storageRESTVersionPrefix + storageRESTMethodCrawlAndGetDataUsage).HandlerFunc(httpTraceHdrs(server.CrawlAndGetDataUsageHandler))
 			subrouter.Methods(http.MethodPost).Path(storageRESTVersionPrefix + storageRESTMethodMakeVol).HandlerFunc(httpTraceHdrs(server.MakeVolHandler)).Queries(restQueries(storageRESTVolume)...)
 			subrouter.Methods(http.MethodPost).Path(storageRESTVersionPrefix + storageRESTMethodStatVol).HandlerFunc(httpTraceHdrs(server.StatVolHandler)).Queries(restQueries(storageRESTVolume)...)
 			subrouter.Methods(http.MethodPost).Path(storageRESTVersionPrefix + storageRESTMethodDeleteVol).HandlerFunc(httpTraceHdrs(server.DeleteVolHandler)).Queries(restQueries(storageRESTVolume)...)

cmd/utils.go

@@ -525,6 +525,16 @@ func getMinioMode() string {
 	return mode
 }
 
+func splitN(str, delim string, num int) []string {
+	stdSplit := strings.SplitN(str, delim, num)
+	retSplit := make([]string, num)
+	for i := 0; i < len(stdSplit); i++ {
+		retSplit[i] = stdSplit[i]
+	}
+
+	return retSplit
+}
+
 func iamPolicyName() string {
 	return globalOpenIDConfig.ClaimPrefix + iampolicy.PolicyName
 }

cmd/xl-v1.go

@@ -20,6 +20,7 @@ import (
 	"context"
 	"sort"
 	"strings"
+	"sync"
 
 	"github.com/minio/minio/cmd/logger"
 	"github.com/minio/minio/pkg/bpool"
@@ -206,3 +207,41 @@ func (xl xlObjects) GetMetrics(ctx context.Context) (*Metrics, error) {
 	logger.LogIf(ctx, NotImplemented{})
 	return &Metrics{}, NotImplemented{}
 }
+
+func (xl xlObjects) crawlAndGetDataUsage(ctx context.Context, endCh <-chan struct{}) DataUsageInfo {
+	var randomDisks []StorageAPI
+	for _, d := range xl.getLoadBalancedDisks() {
+		if d == nil || !d.IsOnline() {
+			continue
+		}
+		if len(randomDisks) > 3 {
+			break
+		}
+		randomDisks = append(randomDisks, d)
+	}
+
+	var dataUsageResults = make([]DataUsageInfo, len(randomDisks))
+
+	var wg sync.WaitGroup
+	for i := 0; i < len(randomDisks); i++ {
+		wg.Add(1)
+		go func(index int, disk StorageAPI) {
+			defer wg.Done()
+			var err error
+			dataUsageResults[index], err = disk.CrawlAndGetDataUsage(endCh)
+			if err != nil {
+				logger.LogIf(ctx, err)
+			}
+		}(i, randomDisks[i])
+	}
+	wg.Wait()
+
+	var dataUsageInfo DataUsageInfo
+	for i := 0; i < len(dataUsageResults); i++ {
+		if dataUsageResults[i].ObjectsCount > dataUsageInfo.ObjectsCount {
+			dataUsageInfo = dataUsageResults[i]
+		}
+	}
+
+	return dataUsageInfo
+}

cmd/xl-zones.go

@@ -23,6 +23,7 @@ import (
 	"math/rand"
 	"net/http"
 	"strings"
+	"sync"
 
 	xhttp "github.com/minio/minio/cmd/http"
 	"github.com/minio/minio/cmd/logger"
@@ -211,6 +212,46 @@ func (z *xlZones) StorageInfo(ctx context.Context) StorageInfo {
 	return storageInfo
 }
 
+func (z *xlZones) crawlAndGetDataUsage(ctx context.Context, endCh <-chan struct{}) DataUsageInfo {
+	var aggDataUsageInfo = struct {
+		sync.Mutex
+		DataUsageInfo
+	}{}
+
+	aggDataUsageInfo.ObjectsSizesHistogram = make(map[string]uint64)
+	aggDataUsageInfo.BucketsSizes = make(map[string]uint64)
+
+	var wg sync.WaitGroup
+	for _, z := range z.zones {
+		for _, xlObj := range z.sets {
+			wg.Add(1)
+			go func(xl *xlObjects) {
+				defer wg.Done()
+				info := xl.crawlAndGetDataUsage(ctx, endCh)
+
+				aggDataUsageInfo.Lock()
+				aggDataUsageInfo.ObjectsCount += info.ObjectsCount
+				aggDataUsageInfo.ObjectsTotalSize += info.ObjectsTotalSize
+				if aggDataUsageInfo.BucketsCount < info.BucketsCount {
+					aggDataUsageInfo.BucketsCount = info.BucketsCount
+				}
+				for k, v := range info.ObjectsSizesHistogram {
+					aggDataUsageInfo.ObjectsSizesHistogram[k] += v
+				}
+				for k, v := range info.BucketsSizes {
+					aggDataUsageInfo.BucketsSizes[k] += v
+				}
+				aggDataUsageInfo.Unlock()
+
+			}(xlObj)
+		}
+	}
+	wg.Wait()
+
+	aggDataUsageInfo.LastUpdate = UTCNow()
+	return aggDataUsageInfo.DataUsageInfo
+}
+
 // This function is used to undo a successful MakeBucket operation.
 func undoMakeBucketZones(bucket string, zones []*xlSets, errs []error) {
 	g := errgroup.WithNErrs(len(zones))

pkg/madmin/examples/data-usage-info.go

@@ -0,0 +1,44 @@
+// +build ignore
+
+/*
+ * MinIO Cloud Storage, (C) 2019 MinIO, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+package main
+
+import (
+	"log"
+
+	"github.com/minio/minio/pkg/madmin"
+)
+
+func main() {
+	// Note: YOUR-ACCESSKEYID, YOUR-SECRETACCESSKEY and my-bucketname are
+	// dummy values, please replace them with original values.
+
+	// API requests are secure (HTTPS) if secure=true and insecure (HTTPS) otherwise.
+	// New returns an MinIO Admin client object.
+	madmClnt, err := madmin.New("your-minio.example.com:9000", "YOUR-ACCESSKEYID", "YOUR-SECRETACCESSKEY", true)
+	if err != nil {
+		log.Fatalln(err)
+	}
+
+	dataUsageInfo, err := madmClnt.DataUsageInfo()
+	if err != nil {
+		log.Fatalln(err)
+	}
+	log.Println(dataUsageInfo)
+}

pkg/madmin/info-commands.go

@@ -24,6 +24,7 @@ import (
 	"net/http"
 	"net/url"
 	"strconv"
+	"time"
 
 	humanize "github.com/dustin/go-humanize"
 	"github.com/minio/minio/pkg/cpu"
@@ -140,6 +141,63 @@ func (adm *AdminClient) StorageInfo() (StorageInfo, error) {
 	return storageInfo, nil
 }
 
+type objectHistogramInterval struct {
+	name       string
+	start, end int64
+}
+
+// ObjectsHistogramIntervals contains the list of intervals
+// of an histogram analysis of objects sizes.
+var ObjectsHistogramIntervals = []objectHistogramInterval{
+	{"LESS_THAN_1024_B", -1, 1024 - 1},
+	{"BETWEEN_1024_B_AND_1_MB", 1024, 1024*1024 - 1},
+	{"BETWEEN_1_MB_AND_10_MB", 1024 * 1024, 1024*1024*10 - 1},
+	{"BETWEEN_10_MB_AND_64_MB", 1024 * 1024 * 10, 1024*1024*64 - 1},
+	{"BETWEEN_64_MB_AND_128_MB", 1024 * 1024 * 64, 1024*1024*128 - 1},
+	{"BETWEEN_128_MB_AND_512_MB", 1024 * 1024 * 128, 1024*1024*512 - 1},
+	{"GREATER_THAN_512_MB", 1024 * 1024 * 512, -1},
+}
+
+// DataUsageInfo represents data usage of an Object API
+type DataUsageInfo struct {
+	LastUpdate            time.Time         `json:"lastUpdate"`
+	ObjectsCount          uint64            `json:"objectsCount"`
+	ObjectsTotalSize      uint64            `json:"objectsTotalSize"`
+	ObjectsSizesHistogram map[string]uint64 `json:"objectsSizesHistogram"`
+
+	BucketsCount uint64            `json:"bucketsCount"`
+	BucketsSizes map[string]uint64 `json:"bucketsSizes"`
+}
+
+// DataUsageInfo - returns data usage of the current object API
+func (adm *AdminClient) DataUsageInfo() (DataUsageInfo, error) {
+	resp, err := adm.executeMethod("GET", requestData{relPath: adminAPIPrefix + "/datausageinfo"})
+	defer closeResponse(resp)
+	if err != nil {
+		return DataUsageInfo{}, err
+	}
+
+	// Check response http status code
+	if resp.StatusCode != http.StatusOK {
+		return DataUsageInfo{}, httpRespToErrorResponse(resp)
+	}
+
+	// Unmarshal the server's json response
+	var dataUsageInfo DataUsageInfo
+
+	respBytes, err := ioutil.ReadAll(resp.Body)
+	if err != nil {
+		return DataUsageInfo{}, err
+	}
+
+	err = json.Unmarshal(respBytes, &dataUsageInfo)
+	if err != nil {
+		return DataUsageInfo{}, err
+	}
+
+	return dataUsageInfo, nil
+}
+
 // ServerDrivesPerfInfo holds informantion about address and write speed of
 // all drives in a single server node
 type ServerDrivesPerfInfo struct {