server: Implement --ignore-disks for ignoring disks from healing. (#2158)

By default server heals/creates missing directories and re-populates
`format.json`, in some scenarios when disk is down for maintainenance
it would be beneficial for users to ignore such disks rather than
mistakenly using `root` partition.

Fixes #2128

format-config-v1.go

@@ -115,27 +115,31 @@ var errSomeDiskOffline = errors.New("some disks are offline")
 var errDiskOrderMismatch = errors.New("disk order mismatch")
 
 // Returns error slice into understandable errors.
-func reduceFormatErrs(errs []error, diskCount int) error {
+func reduceFormatErrs(errs []error, diskCount int) (err error) {
 	var errUnformattedDiskCount = 0
 	var errDiskNotFoundCount = 0
-	for _, err := range errs {
+	for _, dErr := range errs {
-		if err == errUnformattedDisk {
+		if dErr == errUnformattedDisk {
 			errUnformattedDiskCount++
-		} else if err == errDiskNotFound {
+		} else if dErr == errDiskNotFound {
 			errDiskNotFoundCount++
 		}
 	}
+	// Unformatted disks found, we need to figure out if any disks are offline.
+	if errUnformattedDiskCount > 0 {
 		// Returns errUnformattedDisk if all disks report unFormattedDisk.
-	if errUnformattedDiskCount == diskCount {
+		if errUnformattedDiskCount < diskCount {
-		return errUnformattedDisk
+			if errDiskNotFoundCount > 0 {
-	} else if errUnformattedDiskCount < diskCount && errDiskNotFoundCount == 0 {
+				// Only some disks are fresh but some disks are offline as well.
-		// Only some disks return unFormattedDisk and all disks are online.
-		return errSomeDiskUnformatted
-	} else if errUnformattedDiskCount < diskCount && errDiskNotFoundCount > 0 {
-		// Only some disks return unFormattedDisk and some disks are
-		// offline as well.
 				return errSomeDiskOffline
 			}
+			// Some disks are fresh disks an unformatted, not disks are offline.
+			return errSomeDiskUnformatted
+		}
+		// All disks returned unformatted, all disks must be fresh.
+		return errUnformattedDisk
+	}
+	// No unformatted disks found no need to handle disk not found case, return success here.
 	return nil
 }
 
@@ -152,6 +156,10 @@ func loadAllFormats(bootstrapDisks []StorageAPI) ([]*formatConfigV1, []error) {
 
 	// Make a volume entry on all underlying storage disks.
 	for index, disk := range bootstrapDisks {
+		if disk == nil {
+			sErrs[index] = errDiskNotFound
+			continue
+		}
 		wg.Add(1)
 		// Make a volume inside a go-routine.
 		go func(index int, disk StorageAPI) {
@@ -409,6 +417,11 @@ func healFormatXL(storageDisks []StorageAPI) error {
 	var referenceConfig *formatConfigV1
 	// Loads `format.json` from all disks.
 	for index, disk := range storageDisks {
+		// Disk not found or ignored is a valid case.
+		if disk == nil {
+			// Proceed without healing.
+			return nil
+		}
 		formatXL, err := loadFormat(disk)
 		if err != nil {
 			if err == errUnformattedDisk {
@@ -429,11 +442,6 @@ func healFormatXL(storageDisks []StorageAPI) error {
 		return nil
 	}
 
-	// Init meta volume.
-	if err := initMetaVolume(storageDisks); err != nil {
-		return err
-	}
-
 	// All disks are fresh, format.json will be written by initFormatXL()
 	if isFormatNotFound(formatConfigs) {
 		return initFormatXL(storageDisks)
@@ -499,6 +507,10 @@ func loadFormatXL(bootstrapDisks []StorageAPI) (disks []StorageAPI, err error) {
 
 	// Try to load `format.json` bootstrap disks.
 	for index, disk := range bootstrapDisks {
+		if disk == nil {
+			diskNotFoundCount++
+			continue
+		}
 		var formatXL *formatConfigV1
 		formatXL, err = loadFormat(disk)
 		if err != nil {
@@ -515,16 +527,13 @@ func loadFormatXL(bootstrapDisks []StorageAPI) (disks []StorageAPI, err error) {
 		formatConfigs[index] = formatXL
 	}
 
-	// If all disks indicate that 'format.json' is not available
+	// If all disks indicate that 'format.json' is not available return 'errUnformattedDisk'.
-	// return 'errUnformattedDisk'.
+	if unformattedDisksFoundCnt > len(bootstrapDisks)-(len(bootstrapDisks)/2+1) {
-	if unformattedDisksFoundCnt == len(bootstrapDisks) {
 		return nil, errUnformattedDisk
 	} else if diskNotFoundCount == len(bootstrapDisks) {
 		return nil, errDiskNotFound
 	} else if diskNotFoundCount > len(bootstrapDisks)-(len(bootstrapDisks)/2+1) {
 		return nil, errXLReadQuorum
-	} else if unformattedDisksFoundCnt > len(bootstrapDisks)-(len(bootstrapDisks)/2+1) {
-		return nil, errXLReadQuorum
 	}
 
 	// Validate the format configs read are correct.

fs-v1_test.go

@@ -40,7 +40,7 @@ func TestNewFS(t *testing.T) {
 	}
 
 	// Initializes all disks with XL
-	_, err := newXLObjects(disks)
+	_, err := newXLObjects(disks, nil)
 	if err != nil {
 		t.Fatalf("Unable to initialize XL object, %s", err)
 	}

object-common.go

@@ -86,7 +86,7 @@ func initMetaVolume(storageDisks []StorageAPI) error {
 	// Initialize all disks in parallel.
 	for index, disk := range storageDisks {
 		if disk == nil {
-			errs[index] = errDiskNotFound
+			// Ignore create meta volume on disks which are not found.
 			continue
 		}
 		wg.Add(1)
@@ -135,7 +135,6 @@ func xlHouseKeeping(storageDisks []StorageAPI) error {
 	// Initialize all disks in parallel.
 	for index, disk := range storageDisks {
 		if disk == nil {
-			errs[index] = errDiskNotFound
 			continue
 		}
 		wg.Add(1)

routers.go

@@ -23,16 +23,15 @@ import (
 	router "github.com/gorilla/mux"
 )
 
-// newObjectLayer - initialize any object layer depending on the
+// newObjectLayer - initialize any object layer depending on the number of disks.
-// number of export paths.
+func newObjectLayer(disks, ignoredDisks []string) (ObjectLayer, error) {
-func newObjectLayer(exportPaths []string) (ObjectLayer, error) {
+	if len(disks) == 1 {
-	if len(exportPaths) == 1 {
+		exportPath := disks[0]
-		exportPath := exportPaths[0]
 		// Initialize FS object layer.
 		return newFSObjects(exportPath)
 	}
 	// Initialize XL object layer.
-	objAPI, err := newXLObjects(exportPaths)
+	objAPI, err := newXLObjects(disks, ignoredDisks)
 	if err == errXLWriteQuorum {
 		return objAPI, errors.New("Disks are different with last minio server run.")
 	}
@@ -41,11 +40,11 @@ func newObjectLayer(exportPaths []string) (ObjectLayer, error) {
 
 // configureServer handler returns final handler for the http server.
 func configureServerHandler(srvCmdConfig serverCmdConfig) http.Handler {
-	objAPI, err := newObjectLayer(srvCmdConfig.exportPaths)
+	objAPI, err := newObjectLayer(srvCmdConfig.disks, srvCmdConfig.ignoredDisks)
 	fatalIf(err, "Unable to intialize object layer.")
 
 	// Initialize storage rpc server.
-	storageRPC, err := newRPCServer(srvCmdConfig.exportPaths[0]) // FIXME: should only have one path.
+	storageRPC, err := newRPCServer(srvCmdConfig.disks[0]) // FIXME: should only have one path.
 	fatalIf(err, "Unable to initialize storage RPC server.")
 
 	// Initialize API.

server-main.go

@@ -39,6 +39,11 @@ var serverCmd = cli.Command{
 		cli.StringFlag{
 			Name:  "address",
 			Value: ":9000",
+			Usage: "Specify custom server \"ADDRESS:PORT\", defaults to \":9000\".",
+		},
+		cli.StringFlag{
+			Name:  "ignore-disks",
+			Usage: "Specify comma separated list of disks that are offline.",
 		},
 	},
 	Action: serverMain,
@@ -52,9 +57,14 @@ OPTIONS:
   {{range .Flags}}{{.}}
   {{end}}
 ENVIRONMENT VARIABLES:
+  ACCESS:
      MINIO_ACCESS_KEY: Access key string of 5 to 20 characters in length.
      MINIO_SECRET_KEY: Secret key string of 8 to 40 characters in length.
 
+  CACHING:
+     MINIO_CACHE_SIZE: Set total cache size in NN[GB|MB|KB]. Defaults to 8GB.
+     MINIO_CACHE_EXPIRY: Set cache expiration duration in NN[h|m|s]. Defaults to 72 hours.
+
 EXAMPLES:
   1. Start minio server.
       $ minio {{.Name}} /home/shared
@@ -65,16 +75,23 @@ EXAMPLES:
   3. Start minio server on Windows.
       $ minio {{.Name}} C:\MyShare
 
-  4. Start minio server 12 disks to enable erasure coded layer with 6 data and 6 parity.
+  4. Start minio server on 12 disks to enable erasure coded layer with 6 data and 6 parity.
       $ minio {{.Name}} /mnt/export1/backend /mnt/export2/backend /mnt/export3/backend /mnt/export4/backend \
           /mnt/export5/backend /mnt/export6/backend /mnt/export7/backend /mnt/export8/backend /mnt/export9/backend \
           /mnt/export10/backend /mnt/export11/backend /mnt/export12/backend
+
+  5. Start minio server on 12 disks while ignoring two disks for initialization.
+      $ minio {{.Name}} --ignore-disks=/mnt/export1/backend,/mnt/export2/backend /mnt/export1/backend \
+          /mnt/export2/backend /mnt/export3/backend /mnt/export4/backend /mnt/export5/backend /mnt/export6/backend \
+          /mnt/export7/backend /mnt/export8/backend /mnt/export9/backend /mnt/export10/backend /mnt/export11/backend \
+          /mnt/export12/backend
 `,
 }
 
 type serverCmdConfig struct {
 	serverAddr   string
-	exportPaths []string
+	disks        []string
+	ignoredDisks []string
 }
 
 // configureServer configure a new server instance
@@ -292,13 +309,17 @@ func serverMain(c *cli.Context) {
 	// Check if requested port is available.
 	checkPortAvailability(getPort(net.JoinHostPort(host, port)))
 
-	// Save all command line args as export paths.
+	// Disks to be ignored in server init, to skip format healing.
-	exportPaths := c.Args()
+	ignoredDisks := strings.Split(c.String("ignore-disks"), ",")
+
+	// Disks to be used in server init.
+	disks := c.Args()
 
 	// Configure server.
 	apiServer := configureServer(serverCmdConfig{
 		serverAddr:   serverAddress,
-		exportPaths: exportPaths,
+		disks:        disks,
+		ignoredDisks: ignoredDisks,
 	})
 
 	// Credential.

test-utils_test.go

@@ -129,7 +129,7 @@ func StartTestServer(t TestErrHandler, instanceType string) TestServer {
 	testServer.AccessKey = credentials.AccessKeyID
 	testServer.SecretKey = credentials.SecretAccessKey
 	// Run TestServer.
-	testServer.Server = httptest.NewServer(configureServerHandler(serverCmdConfig{exportPaths: erasureDisks}))
+	testServer.Server = httptest.NewServer(configureServerHandler(serverCmdConfig{disks: erasureDisks}))
 
 	return testServer
 }
@@ -632,7 +632,7 @@ func getXLObjectLayer() (ObjectLayer, []string, error) {
 		erasureDisks = append(erasureDisks, path)
 	}
 
-	objLayer, err := newXLObjects(erasureDisks)
+	objLayer, err := newXLObjects(erasureDisks, nil)
 	if err != nil {
 		return nil, nil, err
 	}

xl-v1.go

@@ -93,8 +93,19 @@ func checkSufficientDisks(disks []string) error {
 	return nil
 }
 
+// isDiskFound - validates if the disk is found in a list of input disks.
+func isDiskFound(disk string, disks []string) bool {
+	for _, d := range disks {
+		// Disk found return
+		if disk == d {
+			return true
+		}
+	}
+	return false
+}
+
 // newXLObjects - initialize new xl object layer.
-func newXLObjects(disks []string) (ObjectLayer, error) {
+func newXLObjects(disks, ignoredDisks []string) (ObjectLayer, error) {
 	// Validate if input disks are sufficient.
 	if err := checkSufficientDisks(disks); err != nil {
 		return nil, err
@@ -103,9 +114,14 @@ func newXLObjects(disks []string) (ObjectLayer, error) {
 	// Bootstrap disks.
 	storageDisks := make([]StorageAPI, len(disks))
 	for index, disk := range disks {
+		// Check if disk is ignored.
+		if isDiskFound(disk, ignoredDisks) {
+			storageDisks[index] = nil
+			continue
+		}
 		var err error
-		// Intentionally ignore disk not found errors. XL will
+		// Intentionally ignore disk not found errors. XL is designed
-		// manage such errors internally.
+		// to handle these errors internally.
 		storageDisks[index], err = newStorageAPI(disk)
 		if err != nil && err != errDiskNotFound {
 			return nil, err
@@ -122,12 +138,14 @@ func newXLObjects(disks []string) (ObjectLayer, error) {
 		return nil, err
 	}
 
-	// Handles different cases properly.
+	// Initialize meta volume, if volume already exists ignores it.
-	switch reduceFormatErrs(sErrs, len(storageDisks)) {
-	case errUnformattedDisk:
 	if err := initMetaVolume(storageDisks); err != nil {
 		return nil, fmt.Errorf("Unable to initialize '.minio' meta volume, %s", err)
 	}
+
+	// Handles different cases properly.
+	switch reduceFormatErrs(sErrs, len(storageDisks)) {
+	case errUnformattedDisk:
 		// All drives online but fresh, initialize format.
 		if err := initFormatXL(storageDisks); err != nil {
 			return nil, fmt.Errorf("Unable to initialize format, %s", err)
@@ -139,8 +157,8 @@ func newXLObjects(disks []string) (ObjectLayer, error) {
 			return nil, fmt.Errorf("Unable to heal backend %s", err)
 		}
 	case errSomeDiskOffline:
-		// Some disks offline but some report missing format.json.
+		// FIXME: in future.
-		// FIXME.
+		return nil, fmt.Errorf("Unable to initialize format %s and %s", errSomeDiskOffline, errSomeDiskUnformatted)
 	}
 
 	// Runs house keeping code, like t, cleaning up tmp files etc.

xl-v1_test.go

@@ -132,7 +132,7 @@ func TestNewXL(t *testing.T) {
 		defer removeAll(disk)
 	}
 	// Initializes all erasure disks
-	_, err := newXLObjects(erasureDisks)
+	_, err := newXLObjects(erasureDisks, nil)
 	if err != nil {
 		t.Fatalf("Unable to initialize erasure, %s", err)
 	}