Fix backend format for disk-cache - not to use FS format.json (#5732)

Fixes #5736

cmd/bucket-notification-handlers.go

@@ -138,14 +138,6 @@ func (api objectAPIHandlers) PutBucketNotificationHandler(w http.ResponseWriter,
 		return
 	}
 
-	// Acquire a write lock on bucket before modifying its configuration.
-	bucketLock := globalNSMutex.NewNSLock(bucketName, "")
-	if err = bucketLock.GetLock(globalOperationTimeout); err != nil {
-		writeErrorResponse(w, toAPIErrorCode(err), r.URL)
-		return
-	}
-	defer bucketLock.Unlock()
-
 	if err = saveNotificationConfig(objectAPI, bucketName, config); err != nil {
 		writeErrorResponse(w, toAPIErrorCode(err), r.URL)
 		return

cmd/common-main.go

@@ -20,6 +20,7 @@ import (
 	"errors"
 	"os"
 	"path/filepath"
+	"strconv"
 	"strings"
 	"time"
 
@@ -125,21 +126,22 @@ func handleCommonEnvVars() {
 	}
 
 	if drives := os.Getenv("MINIO_CACHE_DRIVES"); drives != "" {
-		driveList, err := parseCacheDrives(drives)
-		fatalIf(err, "Invalid value set in environment variable MINIO_CACHE_DRIVES")
+		driveList, err := parseCacheDrives(strings.Split(drives, cacheEnvDelimiter))
+		fatalIf(err, "Invalid value set in environment variable MINIO_CACHE_DRIVES %s.", drives)
 		globalCacheDrives = driveList
 		globalIsDiskCacheEnabled = true
 	}
 	if excludes := os.Getenv("MINIO_CACHE_EXCLUDE"); excludes != "" {
-		excludeList, err := parseCacheExcludes(excludes)
-		fatalIf(err, "Invalid value set in environment variable MINIO_CACHE_EXCLUDE")
+		excludeList, err := parseCacheExcludes(strings.Split(excludes, cacheEnvDelimiter))
+		fatalIf(err, "Invalid value set in environment variable MINIO_CACHE_EXCLUDE %s.", excludes)
 		globalCacheExcludes = excludeList
 	}
 	if expiryStr := os.Getenv("MINIO_CACHE_EXPIRY"); expiryStr != "" {
-		expiry, err := parseCacheExpiry(expiryStr)
-		fatalIf(err, "Invalid value set in environment variable MINIO_CACHE_EXPIRY")
+		expiry, err := strconv.Atoi(expiryStr)
+		fatalIf(err, "Invalid value set in environment variable MINIO_CACHE_EXPIRY %s.", expiryStr)
 		globalCacheExpiry = expiry
 	}
+
 	// In place update is true by default if the MINIO_UPDATE is not set
 	// or is not set to 'off', if MINIO_UPDATE is set to 'off' then
 	// in-place update is off.

cmd/config-current.go

@@ -113,14 +113,7 @@ func (s *serverConfig) SetCacheConfig(drives, exclude []string, expiry int) {
 
 // GetCacheConfig gets the current cache config
 func (s *serverConfig) GetCacheConfig() CacheConfig {
-	if s.Cache.Drives != nil {
-		return CacheConfig{
-			Drives:  s.Cache.Drives,
-			Exclude: s.Cache.Exclude,
-			Expiry:  s.Cache.Expiry,
-		}
-	}
-	return CacheConfig{}
+	return s.Cache
 }
 
 // Save config.
@@ -247,6 +240,7 @@ func newConfig() error {
 	if globalIsDiskCacheEnabled {
 		srvCfg.SetCacheConfig(globalCacheDrives, globalCacheExcludes, globalCacheExpiry)
 	}
+
 	// hold the mutex lock before a new config is assigned.
 	// Save the new config globally.
 	// unlock the mutex.
@@ -377,6 +371,7 @@ func loadConfig() error {
 	if globalIsDiskCacheEnabled {
 		srvCfg.SetCacheConfig(globalCacheDrives, globalCacheExcludes, globalCacheExpiry)
 	}
+
 	// hold the mutex lock before a new config is assigned.
 	globalServerConfigMu.Lock()
 	globalServerConfig = srvCfg

cmd/config-migrate.go

@@ -1752,7 +1752,7 @@ func migrateV21ToV22() error {
 	srvConfig := &serverConfigV22{
 		Notify: notifier{},
 	}
-	srvConfig.Version = serverConfigVersion
+	srvConfig.Version = "22"
 	srvConfig.Credential = cv21.Credential
 	srvConfig.Region = cv21.Region
 	if srvConfig.Region == "" {
@@ -1856,7 +1856,7 @@ func migrateV22ToV23() error {
 	srvConfig := &serverConfigV23{
 		Notify: notifier{},
 	}
-	srvConfig.Version = serverConfigVersion
+	srvConfig.Version = "23"
 	srvConfig.Credential = cv22.Credential
 	srvConfig.Region = cv22.Region
 	if srvConfig.Region == "" {
@@ -1934,6 +1934,10 @@ func migrateV22ToV23() error {
 	// Load domain config from existing config in the file.
 	srvConfig.Domain = cv22.Domain
 
+	// Load storage class config from existing storage class config in the file
+	srvConfig.StorageClass.RRS = cv22.StorageClass.RRS
+	srvConfig.StorageClass.Standard = cv22.StorageClass.Standard
+
 	// Init cache config.For future migration, Cache config needs to be copied over from previous version.
 	srvConfig.Cache.Drives = []string{}
 	srvConfig.Cache.Exclude = []string{}

cmd/disk-cache-config.go

@@ -17,48 +17,58 @@
 package cmd
 
 import (
-	"strconv"
-	"strings"
-
-	"errors"
+	"encoding/json"
+	"fmt"
+	"path/filepath"
 )
 
 // CacheConfig represents cache config settings
 type CacheConfig struct {
-	Drives  []string
-	Expiry  int
-	Exclude []string
+	Drives  []string `json:"drives"`
+	Expiry  int      `json:"expiry"`
+	Exclude []string `json:"exclude"`
+}
+
+// UnmarshalJSON - implements JSON unmarshal interface for unmarshalling
+// json entries for CacheConfig.
+func (cfg *CacheConfig) UnmarshalJSON(data []byte) (err error) {
+	type Alias CacheConfig
+	var _cfg = &struct {
+		*Alias
+	}{
+		Alias: (*Alias)(cfg),
+	}
+	if err = json.Unmarshal(data, _cfg); err != nil {
+		return err
+	}
+	if _, err = parseCacheDrives(_cfg.Drives); err != nil {
+		return err
+	}
+	if _, err = parseCacheExcludes(_cfg.Exclude); err != nil {
+		return err
+	}
+	return nil
 }
 
 // Parses given cacheDrivesEnv and returns a list of cache drives.
-func parseCacheDrives(cacheDrivesEnv string) ([]string, error) {
-	cacheDrivesEnv = strings.ToLower(cacheDrivesEnv)
-	s := strings.Split(cacheDrivesEnv, ";")
-	c2 := make([]string, 0)
-	for _, d := range s {
-		if len(d) > 0 {
-			c2 = append(c2, d)
+func parseCacheDrives(drives []string) ([]string, error) {
+	for _, d := range drives {
+		if !filepath.IsAbs(d) {
+			return nil, fmt.Errorf("cache dir should be absolute path: %s", d)
 		}
 	}
-	return c2, nil
+	return drives, nil
 }
 
 // Parses given cacheExcludesEnv and returns a list of cache exclude patterns.
-func parseCacheExcludes(cacheExcludesEnv string) ([]string, error) {
-	s := strings.Split(cacheExcludesEnv, ";")
-	c2 := make([]string, 0)
-	for _, e := range s {
-		if len(e) > 0 {
-			if strings.HasPrefix(e, "/") {
-				return c2, errors.New("cache exclude patterns cannot start with / as prefix " + e)
-			}
-			c2 = append(c2, e)
+func parseCacheExcludes(excludes []string) ([]string, error) {
+	for _, e := range excludes {
+		if len(e) == 0 {
+			return nil, fmt.Errorf("cache exclude path (%s) cannot be empty", e)
+		}
+		if hasPrefix(e, slashSeparator) {
+			return nil, fmt.Errorf("cache exclude pattern (%s) cannot start with / as prefix", e)
 		}
 	}
-	return c2, nil
-}
-
-// Parses given cacheExpiryEnv and returns cache expiry in days.
-func parseCacheExpiry(cacheExpiryEnv string) (int, error) {
-	return strconv.Atoi(cacheExpiryEnv)
+	return excludes, nil
 }

cmd/disk-cache-config_test.go

@@ -18,9 +18,52 @@ package cmd
 
 import (
 	"reflect"
+	"runtime"
+	"strings"
 	"testing"
 )
 
+// Tests cache drive parsing.
+func TestParseCacheDrives(t *testing.T) {
+	testCases := []struct {
+		driveStr         string
+		expectedPatterns []string
+		success          bool
+	}{
+		// valid input
+
+		{"bucket1/*;*.png;images/trip/barcelona/*", []string{}, false},
+		{"bucket1", []string{}, false},
+	}
+	if runtime.GOOS == globalWindowsOSName {
+		testCases = append(testCases, struct {
+			driveStr         string
+			expectedPatterns []string
+			success          bool
+		}{"C:/home/drive1;C:/home/drive2;C:/home/drive3", []string{"C:/home/drive1", "C:/home/drive2", "C:/home/drive3"}, true})
+	} else {
+		testCases = append(testCases, struct {
+			driveStr         string
+			expectedPatterns []string
+			success          bool
+		}{"/home/drive1;/home/drive2;/home/drive3", []string{"/home/drive1", "/home/drive2", "/home/drive3"}, true})
+	}
+	for i, testCase := range testCases {
+		drives, err := parseCacheDrives(strings.Split(testCase.driveStr, cacheEnvDelimiter))
+		if err != nil && testCase.success {
+			t.Errorf("Test %d: Expected success but failed instead %s", i+1, err)
+		}
+		if err == nil && !testCase.success {
+			t.Errorf("Test %d: Expected failure but passed instead", i+1)
+		}
+		if err == nil {
+			if !reflect.DeepEqual(drives, testCase.expectedPatterns) {
+				t.Errorf("Test %d: Expected %v, got %v", i+1, testCase.expectedPatterns, drives)
+			}
+		}
+	}
+}
+
 // Tests cache exclude parsing.
 func TestParseCacheExclude(t *testing.T) {
 	testCases := []struct {
@@ -28,8 +71,6 @@ func TestParseCacheExclude(t *testing.T) {
 		expectedPatterns []string
 		success          bool
 	}{
-		// Empty input.
-		{"", []string{}, true},
 		// valid input
 		{"/home/drive1;/home/drive2;/home/drive3", []string{}, false},
 		{"bucket1/*;*.png;images/trip/barcelona/*", []string{"bucket1/*", "*.png", "images/trip/barcelona/*"}, true},
@@ -37,15 +78,17 @@ func TestParseCacheExclude(t *testing.T) {
 	}
 
 	for i, testCase := range testCases {
-		excludes, err := parseCacheExcludes(testCase.excludeStr)
+		excludes, err := parseCacheExcludes(strings.Split(testCase.excludeStr, cacheEnvDelimiter))
 		if err != nil && testCase.success {
 			t.Errorf("Test %d: Expected success but failed instead %s", i+1, err)
 		}
 		if err == nil && !testCase.success {
 			t.Errorf("Test %d: Expected failure but passed instead", i+1)
 		}
-		if !reflect.DeepEqual(excludes, testCase.expectedPatterns) {
-			t.Errorf("Expected %v, got %v", testCase.expectedPatterns, excludes)
+		if err == nil {
+			if !reflect.DeepEqual(excludes, testCase.expectedPatterns) {
+				t.Errorf("Test %d: Expected %v, got %v", i+1, testCase.expectedPatterns, excludes)
+			}
 		}
 	}
 }

cmd/disk-cache-fs.go

@@ -20,6 +20,7 @@ import (
 	"context"
 	"encoding/hex"
 	"encoding/json"
+	"fmt"
 	"io"
 	"io/ioutil"
 	"os"
@@ -37,6 +38,8 @@ const (
 	// cache.json object metadata for cached objects.
 	cacheMetaJSONFile = "cache.json"
 	cacheMetaFormat   = "cache"
+
+	cacheEnvDelimiter = ";"
 )
 
 // cacheFSObjects implements the cache backend operations.
@@ -59,9 +62,13 @@ type cacheFSObjects struct {
 // Inits the cache directory if it is not init'ed already.
 // Initializing implies creation of new FS Object layer.
 func newCacheFSObjects(dir string, expiry int, maxDiskUsagePct int) (*cacheFSObjects, error) {
-	obj, err := newFSObjects(dir, cacheMetaJSONFile)
-	if err != nil {
-		return nil, err
+	// Assign a new UUID for FS minio mode. Each server instance
+	// gets its own UUID for temporary file transaction.
+	fsUUID := mustGetUUID()
+
+	// Initialize meta volume, if volume already exists ignores it.
+	if err := initMetaVolumeFS(dir, fsUUID); err != nil {
+		return nil, fmt.Errorf("Unable to initialize '.minio.sys' meta volume, %s", err)
 	}
 
 	trashPath := pathJoin(dir, minioMetaBucket, cacheTrashDir)
@@ -72,9 +79,23 @@ func newCacheFSObjects(dir string, expiry int, maxDiskUsagePct int) (*cacheFSObj
 	if expiry == 0 {
 		expiry = globalCacheExpiry
 	}
-	var cacheFS cacheFSObjects
-	fsObjects := obj.(*FSObjects)
-	cacheFS = cacheFSObjects{
+
+	// Initialize fs objects.
+	fsObjects := &FSObjects{
+		fsPath:       dir,
+		metaJSONFile: cacheMetaJSONFile,
+		fsUUID:       fsUUID,
+		rwPool: &fsIOPool{
+			readersMap: make(map[string]*lock.RLockedFile),
+		},
+		nsMutex:       newNSLock(false),
+		listPool:      newTreeWalkPool(globalLookupTimeout),
+		appendFileMap: make(map[string]*fsAppendFile),
+	}
+
+	go fsObjects.cleanupStaleMultipartUploads(globalMultipartCleanupInterval, globalMultipartExpiry, globalServiceDoneCh)
+
+	cacheFS := cacheFSObjects{
 		FSObjects:       fsObjects,
 		dir:             dir,
 		expiry:          expiry,

cmd/disk-cache.go

@@ -18,15 +18,12 @@ package cmd
 
 import (
 	"context"
-	"crypto/sha256"
 	"errors"
 	"fmt"
-	"hash/crc32"
 	"io"
 	"io/ioutil"
 	"net/http"
 	"os"
-	"path"
 	"sort"
 	"strconv"
 	"strings"
@@ -115,7 +112,6 @@ func backendDownError(err error) bool {
 // until an online drive is found.If object is not found, fall back to the first online cache drive
 // closest to the hash index, so that object can be recached.
 func (c diskCache) getCachedFSLoc(ctx context.Context, bucket, object string) (*cacheFSObjects, error) {
-
 	index := c.hashIndex(bucket, object)
 	numDisks := len(c.cfs)
 	// save first online cache disk closest to the hint index
@@ -145,7 +141,6 @@ func (c diskCache) getCachedFSLoc(ctx context.Context, bucket, object string) (*
 // a hint. In the event that the cache drive at hash index is offline, treat the list of cache drives
 // as a circular buffer and walk through them starting at hash index until an online drive is found.
 func (c diskCache) getCacheFS(ctx context.Context, bucket, object string) (*cacheFSObjects, error) {
-
 	index := c.hashIndex(bucket, object)
 	numDisks := len(c.cfs)
 	for k := 0; k < numDisks; k++ {
@@ -162,8 +157,7 @@ func (c diskCache) getCacheFS(ctx context.Context, bucket, object string) (*cach
 
 // Compute a unique hash sum for bucket and object
 func (c diskCache) hashIndex(bucket, object string) int {
-	key := fmt.Sprintf("%x", sha256.Sum256([]byte(path.Join(bucket, object))))
-	return int(crc32.Checksum([]byte(key), crc32.IEEETable)) % len(c.cfs)
+	return crcHashMod(pathJoin(bucket, object), len(c.cfs))
 }
 
 // construct a metadata k-v map
@@ -496,7 +490,6 @@ func (c cacheObjects) listBuckets(ctx context.Context) (buckets []BucketInfo, er
 // Returns list of buckets from cache or the backend. If the backend is down, buckets
 // available on cache are served.
 func (c cacheObjects) ListBuckets(ctx context.Context) (buckets []BucketInfo, err error) {
-
 	listBucketsFn := c.ListBucketsFn
 	buckets, err = listBucketsFn(ctx)
 	if err != nil {
@@ -510,7 +503,6 @@ func (c cacheObjects) ListBuckets(ctx context.Context) (buckets []BucketInfo, er
 
 // Returns bucket info from cache if backend is down.
 func (c cacheObjects) GetBucketInfo(ctx context.Context, bucket string) (bucketInfo BucketInfo, err error) {
-
 	getBucketInfoFn := c.GetBucketInfoFn
 	bucketInfo, err = getBucketInfoFn(ctx, bucket)
 	if backendDownError(err) {
@@ -525,7 +517,6 @@ func (c cacheObjects) GetBucketInfo(ctx context.Context, bucket string) (bucketI
 
 // Delete Object deletes from cache as well if backend operation succeeds
 func (c cacheObjects) DeleteObject(ctx context.Context, bucket, object string) (err error) {
-
 	if err = c.DeleteObjectFn(ctx, bucket, object); err != nil {
 		return
 	}
@@ -619,7 +610,6 @@ func (c cacheObjects) PutObject(ctx context.Context, bucket, object string, r *h
 
 // NewMultipartUpload - Starts a new multipart upload operation to backend and cache.
 func (c cacheObjects) NewMultipartUpload(ctx context.Context, bucket, object string, metadata map[string]string) (uploadID string, err error) {
-
 	newMultipartUploadFn := c.NewMultipartUploadFn
 
 	if c.isCacheExclude(bucket, object) || filterFromCache(metadata) {
@@ -643,7 +633,6 @@ func (c cacheObjects) NewMultipartUpload(ctx context.Context, bucket, object str
 
 // PutObjectPart - uploads part to backend and cache simultaneously.
 func (c cacheObjects) PutObjectPart(ctx context.Context, bucket, object, uploadID string, partID int, data *hash.Reader) (info PartInfo, err error) {
-
 	putObjectPartFn := c.PutObjectPartFn
 	dcache, err := c.cache.getCacheFS(ctx, bucket, object)
 	if err != nil {
@@ -713,7 +702,6 @@ func (c cacheObjects) PutObjectPart(ctx context.Context, bucket, object, uploadI
 
 // AbortMultipartUpload - aborts multipart upload on backend and cache.
 func (c cacheObjects) AbortMultipartUpload(ctx context.Context, bucket, object, uploadID string) error {
-
 	abortMultipartUploadFn := c.AbortMultipartUploadFn
 
 	if c.isCacheExclude(bucket, object) {
@@ -737,7 +725,6 @@ func (c cacheObjects) AbortMultipartUpload(ctx context.Context, bucket, object,
 
 // CompleteMultipartUpload - completes multipart upload operation on backend and cache.
 func (c cacheObjects) CompleteMultipartUpload(ctx context.Context, bucket, object, uploadID string, uploadedParts []CompletePart) (objInfo ObjectInfo, err error) {
-
 	completeMultipartUploadFn := c.CompleteMultipartUploadFn
 
 	if c.isCacheExclude(bucket, object) {
@@ -802,33 +789,32 @@ func (c cacheObjects) DeleteBucket(ctx context.Context, bucket string) (err erro
 
 // newCache initializes the cacheFSObjects for the "drives" specified in config.json
 // or the global env overrides.
-func newCache(c CacheConfig) (*diskCache, error) {
+func newCache(config CacheConfig) (*diskCache, error) {
 	var cfsObjects []*cacheFSObjects
-	formats, err := loadAndValidateCacheFormat(c.Drives)
+	formats, err := loadAndValidateCacheFormat(config.Drives)
 	if err != nil {
-		errorIf(err, "Cache drives validation error")
+		return nil, err
 	}
-	if len(formats) == 0 {
-		return nil, errors.New("Cache drives validation error")
-	}
-	for i, dir := range c.Drives {
+	for i, dir := range config.Drives {
 		// skip cacheFSObjects creation for cache drives missing a format.json
 		if formats[i] == nil {
 			cfsObjects = append(cfsObjects, nil)
 			continue
 		}
-		c, err := newCacheFSObjects(dir, c.Expiry, cacheMaxDiskUsagePct)
-		if err != nil {
-			return nil, err
-		}
 		if err := checkAtimeSupport(dir); err != nil {
 			return nil, errors.New("Atime support required for disk caching")
 		}
+		cache, err := newCacheFSObjects(dir, config.Expiry, cacheMaxDiskUsagePct)
+		if err != nil {
+			return nil, err
+		}
 		// Start the purging go-routine for entries that have expired
-		go c.purge()
+		go cache.purge()
+
 		// Start trash purge routine for deleted buckets.
-		go c.purgeTrash()
-		cfsObjects = append(cfsObjects, c)
+		go cache.purgeTrash()
+
+		cfsObjects = append(cfsObjects, cache)
 	}
 	return &diskCache{cfs: cfsObjects}, nil
 }
@@ -857,17 +843,16 @@ func checkAtimeSupport(dir string) (err error) {
 }
 
 // Returns cacheObjects for use by Server.
-func newServerCacheObjects(c CacheConfig) (CacheObjectLayer, error) {
-
+func newServerCacheObjects(config CacheConfig) (CacheObjectLayer, error) {
 	// list of disk caches for cache "drives" specified in config.json or MINIO_CACHE_DRIVES env var.
-	dcache, err := newCache(c)
+	dcache, err := newCache(config)
 	if err != nil {
 		return nil, err
 	}
 
 	return &cacheObjects{
 		cache:    dcache,
-		exclude:  c.Exclude,
+		exclude:  config.Exclude,
 		listPool: newTreeWalkPool(globalLookupTimeout),
 		GetObjectFn: func(ctx context.Context, bucket, object string, startOffset int64, length int64, writer io.Writer, etag string) error {
 			return newObjectLayerFn().GetObject(ctx, bucket, object, startOffset, length, writer, etag)

cmd/format-disk-cache.go

@@ -21,9 +21,7 @@ import (
 	"fmt"
 	"io"
 	"os"
-	"path/filepath"
 	"reflect"
-	"syscall"
 
 	errors2 "github.com/minio/minio/pkg/errors"
 )
@@ -36,6 +34,8 @@ const (
 	formatCacheVersionV1 = "1"
 
 	formatMetaVersion1 = "1"
+
+	formatCacheV1DistributionAlgo = "CRCMOD"
 )
 
 // Represents the current cache structure with list of
@@ -49,6 +49,9 @@ type formatCacheV1 struct {
 		// Disks field carries the input disk order generated the first
 		// time when fresh disks were supplied.
 		Disks []string `json:"disks"`
+		// Distribution algorithm represents the hashing algorithm
+		// to pick the right set index for an object.
+		DistributionAlgo string `json:"distributionAlgo"`
 	} `json:"cache"` // Cache field holds cache format.
 }
 
@@ -71,6 +74,7 @@ func newFormatCacheV1(drives []string) []*formatCacheV1 {
 		format.Version = formatMetaVersion1
 		format.Format = formatCache
 		format.Cache.Version = formatCacheVersionV1
+		format.Cache.DistributionAlgo = formatCacheV1DistributionAlgo
 		format.Cache.This = mustGetUUID()
 		formats[i] = format
 		disks[i] = formats[i].Cache.This
@@ -116,28 +120,25 @@ func createFormatCache(fsFormatPath string, format *formatCacheV1) error {
 // of format cache config
 func initFormatCache(drives []string) (formats []*formatCacheV1, err error) {
 	nformats := newFormatCacheV1(drives)
-	for i, drive := range drives {
-		// Disallow relative paths, figure out absolute paths.
-		cfsPath, err := filepath.Abs(drive)
-		if err != nil {
+	for _, drive := range drives {
+		_, err = os.Stat(drive)
+		if err == nil {
+			continue
+		}
+		if !os.IsNotExist(err) {
 			return nil, err
 		}
-
-		fi, err := os.Stat(cfsPath)
-		if err == nil {
-			if !fi.IsDir() {
-				return nil, syscall.ENOTDIR
-			}
+		if err = os.Mkdir(drive, 0777); err != nil {
+			return nil, err
 		}
-		if os.IsNotExist(err) {
-			// Disk not found create it.
-			err = os.MkdirAll(cfsPath, 0777)
-			if err != nil {
+	}
+	for i, drive := range drives {
+		if err = os.Mkdir(pathJoin(drive, minioMetaBucket), 0777); err != nil {
+			if !os.IsExist(err) {
 				return nil, err
 			}
 		}
-
-		cacheFormatPath := pathJoin(drive, formatConfigFile)
+		cacheFormatPath := pathJoin(drive, minioMetaBucket, formatConfigFile)
 		// Fresh disk - create format.json for this cfs
 		if err = createFormatCache(cacheFormatPath, nformats[i]); err != nil {
 			return nil, err
@@ -146,32 +147,25 @@ func initFormatCache(drives []string) (formats []*formatCacheV1, err error) {
 	return nformats, nil
 }
 
-func loadFormatCache(drives []string) (formats []*formatCacheV1, err error) {
-	var errs []error
-	for _, drive := range drives {
-		cacheFormatPath := pathJoin(drive, formatConfigFile)
-		f, perr := os.Open(cacheFormatPath)
-		if perr != nil {
-			formats = append(formats, nil)
-			errs = append(errs, perr)
-			continue
+func loadFormatCache(drives []string) ([]*formatCacheV1, error) {
+	formats := make([]*formatCacheV1, len(drives))
+	for i, drive := range drives {
+		cacheFormatPath := pathJoin(drive, minioMetaBucket, formatConfigFile)
+		f, err := os.Open(cacheFormatPath)
+		if err != nil {
+			if os.IsNotExist(err) {
+				continue
+			}
+			return nil, err
 		}
 		defer f.Close()
-		format, perr := formatMetaCacheV1(f)
-		if perr != nil {
-			// format could not be unmarshalled.
-			formats = append(formats, nil)
-			errs = append(errs, perr)
+		format, err := formatMetaCacheV1(f)
+		if err != nil {
 			continue
 		}
-		formats = append(formats, format)
+		formats[i] = format
 	}
-	for _, perr := range errs {
-		if perr != nil {
-			err = perr
-		}
-	}
-	return formats, err
+	return formats, nil
 }
 
 // unmarshalls the cache format.json into formatCacheV1
@@ -198,7 +192,6 @@ func checkFormatCacheValue(format *formatCacheV1) error {
 }
 
 func checkFormatCacheValues(formats []*formatCacheV1) (int, error) {
-
 	for i, formatCache := range formats {
 		if formatCache == nil {
 			continue
@@ -276,6 +269,15 @@ func findCacheDiskIndex(disk string, disks []string) int {
 
 // validate whether cache drives order has changed
 func validateCacheFormats(formats []*formatCacheV1) error {
+	count := 0
+	for _, format := range formats {
+		if format == nil {
+			count++
+		}
+	}
+	if count == len(formats) {
+		return errors.New("Cache format files missing on all drives")
+	}
 	if _, err := checkFormatCacheValues(formats); err != nil {
 		return err
 	}
@@ -290,23 +292,9 @@ func validateCacheFormats(formats []*formatCacheV1) error {
 func cacheDrivesUnformatted(drives []string) bool {
 	count := 0
 	for _, drive := range drives {
-		cacheFormatPath := pathJoin(drive, formatConfigFile)
-
-		// // Disallow relative paths, figure out absolute paths.
-		cfsPath, err := filepath.Abs(cacheFormatPath)
-		if err != nil {
-			continue
-		}
-
-		fi, err := os.Stat(cfsPath)
-		if err == nil {
-			if !fi.IsDir() {
-				continue
-			}
-		}
-		if os.IsNotExist(err) {
+		cacheFormatPath := pathJoin(drive, minioMetaBucket, formatConfigFile)
+		if _, err := os.Stat(cacheFormatPath); os.IsNotExist(err) {
 			count++
-			continue
 		}
 	}
 	return count == len(drives)
@@ -322,7 +310,10 @@ func loadAndValidateCacheFormat(drives []string) (formats []*formatCacheV1, err
 		formats, err = loadFormatCache(drives)
 	}
 	if err != nil {
-		return formats, err
+		return nil, err
 	}
-	return formats, validateCacheFormats(formats)
+	if err = validateCacheFormats(formats); err != nil {
+		return nil, err
+	}
+	return formats, nil
 }

cmd/format-disk-cache_test.go

@@ -27,17 +27,13 @@ func TestDiskCacheFormat(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
-	_, err = initDiskCaches(fsDirs, t)
-	if err != nil {
-		t.Fatal(err)
-	}
-	// cformat := newFormatCacheV1([]string{cacheDataDir + "/format.json"})
+
 	_, err = initFormatCache(fsDirs)
 	if err != nil {
 		t.Fatal(err)
 	}
 	// Do the basic sanity checks to check if initFormatCache() did its job.
-	cacheFormatPath := pathJoin(fsDirs[0], formatConfigFile)
+	cacheFormatPath := pathJoin(fsDirs[0], minioMetaBucket, formatConfigFile)
 	f, err := os.OpenFile(cacheFormatPath, os.O_RDWR, 0)
 	if err != nil {
 		t.Fatal(err)

cmd/fs-v1.go

@@ -95,8 +95,8 @@ func initMetaVolumeFS(fsPath, fsUUID string) error {
 
 }
 
-// newFSObjects - initialize new fs object layer.
-func newFSObjects(fsPath, metaJSONFile string) (ObjectLayer, error) {
+// NewFSObjectLayer - initialize new fs object layer.
+func NewFSObjectLayer(fsPath string) (ObjectLayer, error) {
 	if fsPath == "" {
 		return nil, errInvalidArgument
 	}
@@ -150,7 +150,7 @@ func newFSObjects(fsPath, metaJSONFile string) (ObjectLayer, error) {
 	// Initialize fs objects.
 	fs := &FSObjects{
 		fsPath:       fsPath,
-		metaJSONFile: metaJSONFile,
+		metaJSONFile: fsMetaJSONFile,
 		fsUUID:       fsUUID,
 		rwPool: &fsIOPool{
 			readersMap: make(map[string]*lock.RLockedFile),
@@ -183,11 +183,6 @@ func newFSObjects(fsPath, metaJSONFile string) (ObjectLayer, error) {
 	return fs, nil
 }
 
-// NewFSObjectLayer - initialize new fs object layer.
-func NewFSObjectLayer(fsPath string) (ObjectLayer, error) {
-	return newFSObjects(fsPath, fsMetaJSONFile)
-}
-
 // Shutdown - should be called when process shuts down.
 func (fs *FSObjects) Shutdown(ctx context.Context) error {
 	fs.fsFormatRlk.Close()
@@ -345,12 +340,6 @@ func (fs *FSObjects) DeleteBucket(ctx context.Context, bucket string) error {
 		return toObjectErr(err, bucket)
 	}
 
-	// Cleanup all the previously incomplete multiparts.
-	minioMetaMultipartBucketDir := pathJoin(fs.fsPath, minioMetaMultipartBucket, bucket)
-	if err = fsRemoveAll(minioMetaMultipartBucketDir); err != nil {
-		return toObjectErr(err, bucket)
-	}
-
 	// Cleanup all the bucket metadata.
 	minioMetadataBucketDir := pathJoin(fs.fsPath, minioMetaBucket, bucketMetaPrefix, bucket)
 	if err = fsRemoveAll(minioMetadataBucketDir); err != nil {

cmd/gateway/azure/gateway-azure.go

@@ -19,6 +19,7 @@ package azure
 import (
 	"bytes"
 	"context"
+	"crypto/rand"
 	"encoding/base64"
 	"encoding/hex"
 	"encoding/json"
@@ -38,7 +39,6 @@ import (
 	"github.com/minio/minio/pkg/errors"
 	"github.com/minio/minio/pkg/hash"
 	sha256 "github.com/minio/sha256-simd"
-	"github.com/skyrings/skyring-common/tools/uuid"
 
 	minio "github.com/minio/minio/cmd"
 )
@@ -73,15 +73,15 @@ ENVIRONMENT VARIABLES:
      MINIO_BROWSER: To disable web browser access, set this value to "off".
 
   CACHE:
-     MINIO_CACHE_DRIVES: List of cache drives delimited by ";"
-     MINIO_CACHE_EXCLUDE: List of cache exclusion patterns delimited by ";"
-     MINIO_CACHE_EXPIRY: Cache expiry duration in days
+     MINIO_CACHE_DRIVES: List of cache drives delimited by ";".
+     MINIO_CACHE_EXCLUDE: List of cache exclusion patterns delimited by ";".
+     MINIO_CACHE_EXPIRY: Cache expiry duration in days.
 
   UPDATE:
      MINIO_UPDATE: To turn off in-place upgrades, set this value to "off".
 
   DOMAIN:
-     MINIO_DOMAIN: To enable virtual-host-style requests. Set this value to Minio host domain name.
+     MINIO_DOMAIN: To enable virtual-host-style requests, set this value to Minio host domain name.
 
 EXAMPLES:
   1. Start minio gateway server for Azure Blob Storage backend.
@@ -354,12 +354,20 @@ func azureToObjectError(err error, params ...string) error {
 }
 
 // mustGetAzureUploadID - returns new upload ID which is hex encoded 8 bytes random value.
+// this 8 byte restriction is needed because Azure block id has a restriction of length
+// upto 8 bytes.
 func mustGetAzureUploadID() string {
-	uuid, err := uuid.New()
+	var id [8]byte
+
+	n, err := io.ReadFull(rand.Reader, id[:])
 	if err != nil {
-		panic(err)
+		panic(fmt.Errorf("unable to generate upload ID for azure. %s", err))
 	}
-	return fmt.Sprintf("%x", uuid[:])
+	if n != len(id) {
+		panic(fmt.Errorf("insufficient random data (expected: %d, read: %d)", len(id), n))
+	}
+
+	return hex.EncodeToString(id[:])
 }
 
 // checkAzureUploadID - returns error in case of given string is upload ID.

cmd/gateway/b2/gateway-b2.go

@@ -64,15 +64,15 @@ ENVIRONMENT VARIABLES:
      MINIO_BROWSER: To disable web browser access, set this value to "off".
 
   CACHE:
-     MINIO_CACHE_DRIVES: List of cache drives delimited by ";"
-     MINIO_CACHE_EXCLUDE: List of cache exclusion patterns delimited by ";"
-     MINIO_CACHE_EXPIRY: Cache expiry duration in days
+     MINIO_CACHE_DRIVES: List of cache drives delimited by ";".
+     MINIO_CACHE_EXCLUDE: List of cache exclusion patterns delimited by ";".
+     MINIO_CACHE_EXPIRY: Cache expiry duration in days.
 
   UPDATE:
      MINIO_UPDATE: To turn off in-place upgrades, set this value to "off".
 
   DOMAIN:
-     MINIO_DOMAIN: To enable virtual-host-style requests. Set this value to Minio host domain name.
+     MINIO_DOMAIN: To enable virtual-host-style requests, set this value to Minio host domain name.
 
 EXAMPLES:
   1. Start minio gateway server for B2 backend.

cmd/gateway/gcs/gateway-gcs.go

@@ -110,15 +110,15 @@ ENVIRONMENT VARIABLES:
      MINIO_BROWSER: To disable web browser access, set this value to "off".
 
   CACHE:
-     MINIO_CACHE_DRIVES: List of cache drives delimited by ";"
-     MINIO_CACHE_EXCLUDE: List of cache exclusion patterns delimited by ";"
-     MINIO_CACHE_EXPIRY: Cache expiry duration in days
+     MINIO_CACHE_DRIVES: List of cache drives delimited by ";".
+     MINIO_CACHE_EXCLUDE: List of cache exclusion patterns delimited by ";".
+     MINIO_CACHE_EXPIRY: Cache expiry duration in days.
 
   UPDATE:
      MINIO_UPDATE: To turn off in-place upgrades, set this value to "off".
 
   DOMAIN:
-     MINIO_DOMAIN: To enable virtual-host-style requests. Set this value to Minio host domain name.
+     MINIO_DOMAIN: To enable virtual-host-style requests, set this value to Minio host domain name.
 
   GCS credentials file:
      GOOGLE_APPLICATION_CREDENTIALS: Path to credentials.json

cmd/gateway/manta/gateway-manta.go

@@ -72,12 +72,12 @@ ENVIRONMENT VARIABLES:
      MINIO_BROWSER: To disable web browser access, set this value to "off".
 
   DOMAIN:
-     MINIO_DOMAIN: To enable virtual-host-style requests. Set this value to Minio host domain name.
+     MINIO_DOMAIN: To enable virtual-host-style requests, set this value to Minio host domain name.
 
   CACHE:
-     MINIO_CACHE_DRIVES: List of cache drives delimited by ";"
-     MINIO_CACHE_EXCLUDE: List of cache exclusion patterns delimited by ";"
-     MINIO_CACHE_EXPIRY: Cache expiry duration in days
+     MINIO_CACHE_DRIVES: List of cache drives delimited by ";".
+     MINIO_CACHE_EXCLUDE: List of cache exclusion patterns delimited by ";".
+     MINIO_CACHE_EXPIRY: Cache expiry duration in days.
 
 EXAMPLES:
   1. Start minio gateway server for Manta Object Storage backend.

cmd/gateway/nas/gateway-nas.go

@@ -51,15 +51,15 @@ ENVIRONMENT VARIABLES:
      MINIO_BROWSER: To disable web browser access, set this value to "off".
 
   CACHE:
-     MINIO_CACHE_DRIVES: List of cache drives delimited by ";"
-     MINIO_CACHE_EXCLUDE: List of cache exclusion patterns delimited by ";"
-     MINIO_CACHE_EXPIRY: Cache expiry duration in days
+     MINIO_CACHE_DRIVES: List of cache drives delimited by ";".
+     MINIO_CACHE_EXCLUDE: List of cache exclusion patterns delimited by ";".
+     MINIO_CACHE_EXPIRY: Cache expiry duration in days.
 
   UPDATE:
      MINIO_UPDATE: To turn off in-place upgrades, set this value to "off".
 
   DOMAIN:
-     MINIO_DOMAIN: To enable virtual-host-style requests. Set this value to Minio host domain name.
+     MINIO_DOMAIN: To enable virtual-host-style requests, set this value to Minio host domain name.
 
 EXAMPLES:
   1. Start minio gateway server for NAS backend.

cmd/gateway/oss/gateway-oss.go

@@ -69,12 +69,12 @@ ENVIRONMENT VARIABLES:
      MINIO_UPDATE: To turn off in-place upgrades, set this value to "off".
 
   DOMAIN:
-     MINIO_DOMAIN: To enable virtual-host-style requests. Set this value to Minio host domain name.
+     MINIO_DOMAIN: To enable virtual-host-style requests, set this value to Minio host domain name.
 	
   CACHE:
-     MINIO_CACHE_DRIVES: List of cache drives delimited by ";"
-     MINIO_CACHE_EXCLUDE: List of cache exclusion patterns delimited by ";"
-     MINIO_CACHE_EXPIRY: Cache expiry duration in days
+     MINIO_CACHE_DRIVES: List of cache drives delimited by ";".
+     MINIO_CACHE_EXCLUDE: List of cache exclusion patterns delimited by ";".
+     MINIO_CACHE_EXPIRY: Cache expiry duration in days.
 
 EXAMPLES:
   1. Start minio gateway server for Aliyun OSS backend.

cmd/gateway/s3/gateway-s3.go

@@ -57,15 +57,15 @@ ENVIRONMENT VARIABLES:
      MINIO_BROWSER: To disable web browser access, set this value to "off".
 
   CACHE:
-     MINIO_CACHE_DRIVES: List of cache drives delimited by ";"
-     MINIO_CACHE_EXCLUDE: List of cache exclusion patterns delimited by ";"
-     MINIO_CACHE_EXPIRY: Cache expiry duration in days
+     MINIO_CACHE_DRIVES: List of cache drives delimited by ";".
+     MINIO_CACHE_EXCLUDE: List of cache exclusion patterns delimited by ";".
+     MINIO_CACHE_EXPIRY: Cache expiry duration in days.
 
   UPDATE:
      MINIO_UPDATE: To turn off in-place upgrades, set this value to "off".
 
   DOMAIN:
-     MINIO_DOMAIN: To enable virtual-host-style requests. Set this value to Minio host domain name.
+     MINIO_DOMAIN: To enable virtual-host-style requests, set this value to Minio host domain name.
 
 EXAMPLES:
   1. Start minio gateway server for AWS S3 backend.

cmd/gateway/sia/gateway-sia.go

@@ -74,15 +74,15 @@ ENVIRONMENT VARIABLES: (Default values in parenthesis)
      MINIO_BROWSER: To disable web browser access, set this value to "off".
 
   CACHE:
-     MINIO_CACHE_DRIVES: List of cache drives delimited by ";"
-     MINIO_CACHE_EXCLUDE: List of cache exclusion patterns delimited by ";"
-     MINIO_CACHE_EXPIRY: Cache expiry duration in days
+     MINIO_CACHE_DRIVES: List of cache drives delimited by ";".
+     MINIO_CACHE_EXCLUDE: List of cache exclusion patterns delimited by ";".
+     MINIO_CACHE_EXPIRY: Cache expiry duration in days.
 
   UPDATE:
      MINIO_UPDATE: To turn off in-place upgrades, set this value to "off".
 
   DOMAIN:
-     MINIO_DOMAIN: To enable virtual-host-style requests. Set this value to Minio host domain name.
+     MINIO_DOMAIN: To enable virtual-host-style requests, set this value to Minio host domain name.
 
   SIA_TEMP_DIR:        The name of the local Sia temporary storage directory. (.sia_temp)
   SIA_API_PASSWORD:    API password for Sia daemon. (default is empty)

cmd/notification.go

@@ -496,14 +496,6 @@ func readConfig(objAPI ObjectLayer, configFile string) (*bytes.Buffer, error) {
 func readNotificationConfig(objAPI ObjectLayer, bucketName string) (*event.Config, error) {
 	// Construct path to notification.xml for the given bucket.
 	configFile := path.Join(bucketConfigPrefix, bucketName, bucketNotificationConfig)
-
-	// Get read lock.
-	objLock := globalNSMutex.NewNSLock(minioMetaBucket, configFile)
-	if err := objLock.GetRLock(globalOperationTimeout); err != nil {
-		return nil, err
-	}
-	defer objLock.RUnlock()
-
 	reader, err := readConfig(objAPI, configFile)
 	if err != nil {
 		return nil, err
@@ -519,14 +511,6 @@ func saveNotificationConfig(objAPI ObjectLayer, bucketName string, config *event
 	}
 
 	configFile := path.Join(bucketConfigPrefix, bucketName, bucketNotificationConfig)
-
-	// Get write lock.
-	objLock := globalNSMutex.NewNSLock(minioMetaBucket, configFile)
-	if err := objLock.GetLock(globalOperationTimeout); err != nil {
-		return err
-	}
-	defer objLock.Unlock()
-
 	return saveConfig(objAPI, configFile, data)
 }
 

cmd/posix_test.go

@@ -1282,9 +1282,9 @@ func TestPosixAppendFile(t *testing.T) {
 		expectedErr error
 	}{"level0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001/level0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000002/level0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000003/object000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001", err})
 
-	for _, testCase := range testCases {
+	for i, testCase := range testCases {
 		if err = posixStorage.AppendFile("success-vol", testCase.fileName, []byte("hello, world")); err != testCase.expectedErr {
-			t.Errorf("Case: %s, expected: %s, got: %s", testCase, testCase.expectedErr, err)
+			t.Errorf("Case: %d, expected: %s, got: %s", i+1, testCase.expectedErr, err)
 		}
 	}
 
@@ -1373,9 +1373,9 @@ func TestPosixPrepareFile(t *testing.T) {
 		expectedErr error
 	}{"level0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001/level0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000002/level0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000003/object000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001", err})
 
-	for _, testCase := range testCases {
+	for i, testCase := range testCases {
 		if err = posixStorage.PrepareFile("success-vol", testCase.fileName, 16); err != testCase.expectedErr {
-			t.Errorf("Case: %s, expected: %s, got: %s", testCase, testCase.expectedErr, err)
+			t.Errorf("Case: %d, expected: %s, got: %s", i, testCase.expectedErr, err)
 		}
 	}
 

cmd/server-main.go

@@ -68,9 +68,9 @@ ENVIRONMENT VARIABLES:
      MINIO_BROWSER: To disable web browser access, set this value to "off".
 
   CACHE:
-     MINIO_CACHE_DRIVES: List of cache drives delimited by ";"
-     MINIO_CACHE_EXCLUDE: List of cache exclusion patterns delimited by ";"
-     MINIO_CACHE_EXPIRY: Cache expiry duration in days
+     MINIO_CACHE_DRIVES: List of cache drives delimited by ";".
+     MINIO_CACHE_EXCLUDE: List of cache exclusion patterns delimited by ";".
+     MINIO_CACHE_EXPIRY: Cache expiry duration in days.
 	
   REGION:
      MINIO_REGION: To set custom region. By default all regions are accepted.
@@ -79,7 +79,7 @@ ENVIRONMENT VARIABLES:
      MINIO_UPDATE: To turn off in-place upgrades, set this value to "off".
 
   DOMAIN:
-     MINIO_DOMAIN: To enable virtual-host-style requests. Set this value to Minio host domain name.
+     MINIO_DOMAIN: To enable virtual-host-style requests, set this value to Minio host domain name.
 
   WORM:
      MINIO_WORM: To turn on Write-Once-Read-Many in server, set this value to "on".

cmd/update-main.go

@@ -244,7 +244,7 @@ func getUserAgent(mode string) string {
 	if mode != "" {
 		uaAppend("; ", mode)
 	}
-	if globalIsDiskCacheEnabled {
+	if len(globalCacheDrives) > 0 {
 		uaAppend("; ", "feature-cache")
 	}
 	if globalWORMEnabled {

docs/disk-caching/DESIGN.md

@@ -0,0 +1,48 @@
+# Disk Caching Design [![Slack](https://slack.minio.io/slack?type=svg)](https://slack.minio.io)
+
+This document explains some basic assumptions and design approach, limits of the disk caching feature. If you're looking to get started with disk cache, we suggest you go through the [getting started document](https://github.com/minio/minio/blob/master/docs/disk-caching/README.md) first.
+
+## Command-line
+
+```
+minio server -h
+...
+...
+  CACHE:
+     MINIO_CACHE_DRIVES: List of cache drives delimited by ";"
+     MINIO_CACHE_EXCLUDE: List of cache exclusion patterns delimited by ";"
+     MINIO_CACHE_EXPIRY: Cache expiry duration in days
+...
+...
+
+  7. Start minio server with edge caching enabled on '/drive1', '/drive2' and '/drive3',
+     exclude all objects under 'mybucket', exclude all objects with '.pdf' as extension
+     with expiry upto 40 days.
+     $ export MINIO_CACHE_DRIVES="/drive1;/drive2;/drive3"
+     $ export MINIO_CACHE_EXCLUDE="mybucket/*;*.pdf"
+     $ export MINIO_CACHE_EXPIRY=40
+     $ minio server /home/shared
+```
+
+## Assumptions
+- Disk cache size defaults to 80% of your drive capacity.
+- Disk caching requires [`atime`](http://kerolasa.github.io/filetimes.html) support to be enabled on the cache drive.
+- Expiration of each cached entry takes user provided expiry as a hint, and defaults to 90 days if not provided.
+- Garbage collection sweep of the expired cache entries happens whenever cache usage is > 80% of drive capacity, GC continues until sufficient disk space is reclaimed.
+- An object is only cached when drive has sufficient disk space, upto 100 times the size of the object.
+
+## Behavior
+Disk caching caches objects for both **uploaded** and **downloaded** objects i.e
+
+- Caches new objects for entries not found in cache while downloading. Otherwise serves from the cache.
+- Caches all successfully uploaded objects. Replaces existing cached entry of the same object if needed.
+- When an object is deleted, corresponding entry in cache if any is deleted as well.
+- Cache continues to work for read-only operations such as GET, HEAD when backend is offline.
+- Cache disallows write operations when backend is offline.
+
+> NOTE: Expiration happens automatically based on the configured interval as explained above, frequently accessed objects stay alive in cache for a significantly longer time.
+
+## Limits
+- Bucket policies are not cached, so anonymous operations are not supported when backend is offline.
+- Objects are distributed using deterministic hashing among the list of configured cache drives. If one or more drives go offline, or cache drive configuration is altered in any way, performance may degrade to a linear lookup time depending on the number of disks in cache.
+

docs/disk-caching/README.md

@@ -1,55 +1,41 @@
-## Disk based caching
+# Disk Cache Quickstart Guide [![Slack](https://slack.minio.io/slack?type=svg)](https://slack.minio.io)
 
-Disk caching can be turned on by updating the "cache" config
-settings for minio server. By default, this is at `${HOME}/.minio`.
+Disk caching feature here refers to the use of caching disks to store content closer to the tenants. For instance, if you access an object from a lets say `gateway azure` setup and download the object that gets cached, each subsequent request on the object gets served directly from the cache drives until it expires. This feature allows Minio users to have
 
-"cache" takes the drives location, duration to expiry (in days) and any
-wildcard patterns to exclude certain content from cache as 
-configuration settings. 
-```
+- Object to be delivered with the best possible performance.
+- Dramatic improvements for time to first byte for any object.
+
+## Get started
+
+### 1. Prerequisites
+Install Minio - [Minio Quickstart Guide](https://docs.minio.io/docs/minio).
+
+### 2. Run Minio with cache
+Disk caching can be enabled by updating the `cache` config settings for Minio server. Config `cache` settings takes the drive locations, cache expiry duration (in days) and any wildcard patterns to exclude from being cached.
+
+```json
 "cache": {
-	"drives": ["/path/drive1", "/path/drive2", "/path/drive3"],
-	"expiry": 30,
-	"exclude": ["*.png","bucket1/a/b","bucket2/*"]
+	"drives": ["/drive1", "/drive2", "/drive3"],
+	"expiry": 90,
+	"exclude": ["*.pdf","mybucket/*"]
 },
 ```
 
-The cache settings can also be set by the environment variables
-below. When set, environment variables override any cache settings in config.json
-```
+The cache settings may also be set through environment variables. When set, environment variables override any `cache` config settings for Minio server. Following example uses `/drive1`, `/drive2` and `/drive3` for caching, with expiry upto 90 days while excluding all objects under bucket `mybucket` and all objects with '.pdf' as extension while starting a standalone erasure coded setup.
+
+```bash
 export MINIO_CACHE_DRIVES="/drive1;/drive2;/drive3"
 export MINIO_CACHE_EXPIRY=90
-export MINIO_CACHE_EXCLUDE="pattern1;pattern2;pattern3"
+export MINIO_CACHE_EXCLUDE="*.pdf;mybucket/*"
+minio server /export{1...24}
 ```
 
- - Cache size is 80% of drive capacity. Disk caching requires
-   Atime support to be enabled on the cache drive.
+### 3. Test your setup
+To test this setup, access the Minio server via browser or [`mc`](https://docs.minio.io/docs/minio-client-quickstart-guide). You’ll see the uploaded files are accessible from the all the Minio endpoints.
 
- - Expiration of entries takes user provided expiry as a hint,
-   and defaults to 90 days if not provided.
-
- - Garbage collection sweep of the expired entries happens whenever
-   disk usage is > 80% of drive capacity until sufficient disk
-   space has been freed.
- - Object is cached only when drive has sufficient disk space for 100 times the size of current object
-
-### Behavior
-
-Disk caching happens on both GET and PUT operations.
-
-- GET caches new objects for entries not found in cache.
-  Otherwise serves from the cache.
-
-- PUT/POST caches all successfully uploaded objects. Replaces
-  existing cached entry for the same object if needed.
-
-When an object is deleted, it is automatically cleared from the cache.
-
-NOTE: Expiration happens automatically based on the configured
-interval as explained above, frequently accessed objects stay
-alive in cache for a significantly longer time on every cache hit.
-
-The following caveats apply for offline mode
-  - GET, LIST and HEAD operations will be served from the disk cache.
-  - PUT operations are disallowed when gateway backend is offline.
-  - Anonymous operations are not implemented as of now.
+# Explore Further
+- [Use `mc` with Minio Server](https://docs.minio.io/docs/minio-client-quickstart-guide)
+- [Use `aws-cli` with Minio Server](https://docs.minio.io/docs/aws-cli-with-minio)
+- [Use `s3cmd` with Minio Server](https://docs.minio.io/docs/s3cmd-with-minio)
+- [Use `minio-go` SDK with Minio Server](https://docs.minio.io/docs/golang-client-quickstart-guide)
+- [The Minio documentation website](https://docs.minio.io)

docs/large-bucket/DESIGN.md

@@ -1,7 +1,6 @@
 # Large Bucket Support Design Guide [![Slack](https://slack.minio.io/slack?type=svg)](https://slack.minio.io)
 
-This document explains the design approach, advanced use cases and limitations of the large bucket feature. If you're looking to get started with large bucket support, we suggest you 
-go through the [getting started document](https://github.com/minio/minio/blob/master/docs/large-bucket/README.md) first.
+This document explains the design approach, advanced use cases and limits of the large bucket feature. If you're looking to get started with large bucket support, we suggest you go through the [getting started document](https://github.com/minio/minio/blob/master/docs/large-bucket/README.md) first.
 
 ## Command-line
 

docs/orchestration/docker-compose/docker-compose.yaml

@@ -5,7 +5,7 @@ version: '2'
 # 9001 through 9004.
 services:
  minio1:
-  image: minio/minio:RELEASE.2018-03-19T19-22-06Z
+  image: minio/minio:RELEASE.2018-03-28T23-45-53Z
   volumes:
    - data1:/data
   ports:
@@ -15,7 +15,7 @@ services:
    MINIO_SECRET_KEY: minio123
   command: server http://minio1/data http://minio2/data http://minio3/data http://minio4/data 
  minio2:
-  image: minio/minio:RELEASE.2018-03-19T19-22-06Z
+  image: minio/minio:RELEASE.2018-03-28T23-45-53Z
   volumes:
    - data2:/data
   ports:
@@ -25,7 +25,7 @@ services:
    MINIO_SECRET_KEY: minio123
   command: server http://minio1/data http://minio2/data http://minio3/data http://minio4/data 
  minio3:
-  image: minio/minio:RELEASE.2018-03-19T19-22-06Z
+  image: minio/minio:RELEASE.2018-03-28T23-45-53Z
   volumes:
    - data3:/data
   ports:
@@ -35,7 +35,7 @@ services:
    MINIO_SECRET_KEY: minio123
   command: server http://minio1/data http://minio2/data http://minio3/data http://minio4/data 
  minio4:
-  image: minio/minio:RELEASE.2018-03-19T19-22-06Z
+  image: minio/minio:RELEASE.2018-03-28T23-45-53Z
   volumes:
    - data4:/data
   ports:

docs/orchestration/docker-swarm/docker-compose-secrets.yaml

@@ -2,7 +2,7 @@ version: '3.1'
 
 services:
   minio1:
-    image: minio/minio:RELEASE.2018-03-19T19-22-06Z
+    image: minio/minio:RELEASE.2018-03-28T23-45-53Z
     volumes:
       - minio1-data:/export
     ports:
@@ -20,7 +20,7 @@ services:
       - access_key
 
   minio2:
-    image: minio/minio:RELEASE.2018-03-19T19-22-06Z
+    image: minio/minio:RELEASE.2018-03-28T23-45-53Z
     volumes:
       - minio2-data:/export
     ports:
@@ -38,7 +38,7 @@ services:
       - access_key
 
   minio3:
-    image: minio/minio:RELEASE.2018-03-19T19-22-06Z
+    image: minio/minio:RELEASE.2018-03-28T23-45-53Z
     volumes:
       - minio3-data:/export
     ports:
@@ -56,7 +56,7 @@ services:
       - access_key
 
   minio4:
-    image: minio/minio:RELEASE.2018-03-19T19-22-06Z
+    image: minio/minio:RELEASE.2018-03-28T23-45-53Z
     volumes:
       - minio4-data:/export
     ports:

docs/orchestration/docker-swarm/docker-compose.yaml

@@ -2,7 +2,7 @@ version: '3'
 
 services:
   minio1:
-    image: minio/minio:RELEASE.2018-03-19T19-22-06Z
+    image: minio/minio:RELEASE.2018-03-28T23-45-53Z
     volumes:
       - minio1-data:/export
     ports:
@@ -20,7 +20,7 @@ services:
     command: server http://minio1/export http://minio2/export http://minio3/export http://minio4/export
 
   minio2:
-    image: minio/minio:RELEASE.2018-03-19T19-22-06Z
+    image: minio/minio:RELEASE.2018-03-28T23-45-53Z
     volumes:
       - minio2-data:/export
     ports:
@@ -38,7 +38,7 @@ services:
     command: server http://minio1/export http://minio2/export http://minio3/export http://minio4/export
 
   minio3:
-    image: minio/minio:RELEASE.2018-03-19T19-22-06Z
+    image: minio/minio:RELEASE.2018-03-28T23-45-53Z
     volumes:
       - minio3-data:/export
     ports:
@@ -56,7 +56,7 @@ services:
     command: server http://minio1/export http://minio2/export http://minio3/export http://minio4/export
 
   minio4:
-    image: minio/minio:RELEASE.2018-03-19T19-22-06Z
+    image: minio/minio:RELEASE.2018-03-28T23-45-53Z
     volumes:
       - minio4-data:/export
     ports:

docs/orchestration/kubernetes-yaml/README.md

@@ -123,7 +123,7 @@ spec:
         - name: data 
           mountPath: "/data"
         # Pulls the lastest Minio image from Docker Hub
-        image: minio/minio:RELEASE.2018-03-19T19-22-06Z
+        image: minio/minio:RELEASE.2018-03-28T23-45-53Z
         args:
         - server
         - /data
@@ -302,7 +302,7 @@ spec:
           value: "minio"
         - name: MINIO_SECRET_KEY
           value: "minio123"
-        image: minio/minio:RELEASE.2018-03-19T19-22-06Z
+        image: minio/minio:RELEASE.2018-03-28T23-45-53Z
         args:
         - server
         - http://minio-0.minio.default.svc.cluster.local/data
@@ -484,7 +484,7 @@ spec:
       containers:
       - name: minio
         # Pulls the default Minio image from Docker Hub
-        image: minio/minio:RELEASE.2018-03-19T19-22-06Z
+        image: minio/minio:RELEASE.2018-03-28T23-45-53Z
         args:
         - gateway
         - gcs

docs/orchestration/kubernetes-yaml/minio-distributed-statefulset.yaml

@@ -21,7 +21,7 @@ spec:
           value: "minio"
         - name: MINIO_SECRET_KEY
           value: "minio123"
-        image: minio/minio:RELEASE.2018-03-19T19-22-06Z
+        image: minio/minio:RELEASE.2018-03-28T23-45-53Z
         args:
         - server
         - http://minio-0.minio.default.svc.cluster.local/data

docs/orchestration/kubernetes-yaml/minio-gcs-gateway-deployment.yaml

@@ -21,7 +21,7 @@ spec:
       containers:
       - name: minio
         # Pulls the default Minio image from Docker Hub
-        image: minio/minio:RELEASE.2018-03-19T19-22-06Z
+        image: minio/minio:RELEASE.2018-03-28T23-45-53Z
         args:
         - gateway
         - gcs

docs/orchestration/kubernetes-yaml/minio-standalone-deployment.yaml

@@ -29,7 +29,7 @@ spec:
         - name: data 
           mountPath: "/data"
         # Pulls the lastest Minio image from Docker Hub
-        image: minio/minio:RELEASE.2018-03-19T19-22-06Z
+        image: minio/minio:RELEASE.2018-03-28T23-45-53Z
         args:
         - server
         - /data

docs/orchestration/kubernetes/README.md

@@ -30,7 +30,7 @@ Above command deploys Minio on the Kubernetes cluster in the default configurati
 | Parameter                  | Description                         | Default                                                 |
 |----------------------------|-------------------------------------|---------------------------------------------------------|
 | `image`                    | Minio image name                    | `minio/minio`                                           |
-| `imageTag`                 | Minio image tag. Possible values listed [here](https://hub.docker.com/r/minio/minio/tags/).| `RELEASE.2018-03-19T19-22-06Z`|
+| `imageTag`                 | Minio image tag. Possible values listed [here](https://hub.docker.com/r/minio/minio/tags/).| `RELEASE.2018-03-28T23-45-53Z`|
 | `imagePullPolicy`          | Image pull policy                   | `Always`                                                |
 | `mode`                     | Minio server mode (`standalone`, `shared` or `distributed`)| `standalone`                     |
 | `numberOfNodes`            | Number of nodes (applicable only for Minio distributed mode). Should be 4 <= x <= 16 | `4`    |

docs/orchestration/minikube/statefulset.yaml

@@ -54,7 +54,7 @@ spec:
           value: "minio"
         - name: MINIO_SECRET_KEY
           value: "minio123"
-        image: minio/minio:RELEASE.2018-03-19T19-22-06Z
+        image: minio/minio:RELEASE.2018-03-28T23-45-53Z
         imagePullPolicy: IfNotPresent
         args: ["server", "http://minio-0.minio.default.svc.cluster.local/data", "http://minio-1.minio.default.svc.cluster.local/data", "http://minio-2.minio.default.svc.cluster.local/data", "http://minio-3.minio.default.svc.cluster.local/data"]
         ports: