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178 lines
4.8 KiB
178 lines
4.8 KiB
![]()
8 years ago
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/*
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* Minio Cloud Storage, (C) 2016 Minio, Inc.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package main
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import (
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"errors"
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"fmt"
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"path/filepath"
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"strings"
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"sync"
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)
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const (
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formatConfigFile = "format.json"
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xlMetaJSONFile = "xl.json"
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uploadsJSONFile = "uploads.json"
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)
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// xlObjects - Implements fs object layer.
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type xlObjects struct {
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storageDisks []StorageAPI
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erasureDisk *erasure
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dataBlocks int
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parityBlocks int
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readQuorum int
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writeQuorum int
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listObjectMap map[listParams][]*treeWalker
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listObjectMapMutex *sync.Mutex
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}
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// errMaxDisks - returned for reached maximum of disks.
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var errMaxDisks = errors.New("Number of disks are higher than supported maximum count '16'")
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// errMinDisks - returned for minimum number of disks.
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var errMinDisks = errors.New("Number of disks are smaller than supported minimum count '8'")
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// errNumDisks - returned for odd number of disks.
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var errNumDisks = errors.New("Number of disks should be multiples of '2'")
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const (
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// Maximum erasure blocks.
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maxErasureBlocks = 16
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// Minimum erasure blocks.
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minErasureBlocks = 8
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)
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func checkSufficientDisks(disks []string) error {
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// Verify total number of disks.
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totalDisks := len(disks)
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if totalDisks > maxErasureBlocks {
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return errMaxDisks
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}
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if totalDisks < minErasureBlocks {
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return errMinDisks
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}
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// isEven function to verify if a given number if even.
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isEven := func(number int) bool {
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return number%2 == 0
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}
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// Verify if we have even number of disks.
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// only combination of 8, 10, 12, 14, 16 are supported.
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if !isEven(totalDisks) {
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return errNumDisks
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}
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return nil
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}
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// Depending on the disk type network or local, initialize storage layer.
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func newStorageLayer(disk string) (storage StorageAPI, err error) {
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if !strings.ContainsRune(disk, ':') || filepath.VolumeName(disk) != "" {
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// Initialize filesystem storage API.
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return newPosix(disk)
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}
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// Initialize rpc client storage API.
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return newRPCClient(disk)
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}
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// Initialize all storage disks to bootstrap.
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func bootstrapDisks(disks []string) ([]StorageAPI, error) {
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storageDisks := make([]StorageAPI, len(disks))
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for index, disk := range disks {
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var err error
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// Intentionally ignore disk not found errors while
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// initializing POSIX, so that we have successfully
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// initialized posix Storage. Subsequent calls to XL/Erasure
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// will manage any errors related to disks.
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storageDisks[index], err = newStorageLayer(disk)
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if err != nil && err != errDiskNotFound {
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return nil, err
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}
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}
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return storageDisks, nil
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}
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// newXLObjects - initialize new xl object layer.
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func newXLObjects(disks []string) (ObjectLayer, error) {
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if err := checkSufficientDisks(disks); err != nil {
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return nil, err
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}
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// Bootstrap disks.
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storageDisks, err := bootstrapDisks(disks)
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if err != nil {
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return nil, err
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}
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// Initialize object layer - like creating minioMetaBucket, cleaning up tmp files etc.
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initObjectLayer(storageDisks...)
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// Load saved XL format.json and validate.
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newPosixDisks, err := loadFormatXL(storageDisks)
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if err != nil {
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switch err {
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case errUnformattedDisk:
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// Save new XL format.
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errSave := initFormatXL(storageDisks)
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if errSave != nil {
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return nil, errSave
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}
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newPosixDisks = storageDisks
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default:
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// errCorruptedDisk - error.
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return nil, fmt.Errorf("Unable to recognize backend format, %s", err)
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}
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}
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// FIXME: healFormatXL(newDisks)
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newErasureDisk, err := newErasure(newPosixDisks)
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if err != nil {
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return nil, err
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}
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// Calculate data and parity blocks.
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dataBlocks, parityBlocks := len(newPosixDisks)/2, len(newPosixDisks)/2
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xl := xlObjects{
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storageDisks: newPosixDisks,
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erasureDisk: newErasureDisk,
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dataBlocks: dataBlocks,
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parityBlocks: parityBlocks,
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listObjectMap: make(map[listParams][]*treeWalker),
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listObjectMapMutex: &sync.Mutex{},
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}
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// Figure out read and write quorum based on number of storage disks.
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// Read quorum should be always N/2 + 1 (due to Vandermonde matrix
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// erasure requirements)
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xl.readQuorum = len(xl.storageDisks)/2 + 1
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// Write quorum is assumed if we have total disks + 3
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// parity. (Need to discuss this again)
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xl.writeQuorum = len(xl.storageDisks)/2 + 3
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if xl.writeQuorum > len(xl.storageDisks) {
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xl.writeQuorum = len(xl.storageDisks)
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}
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// Return successfully initialized object layer.
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return xl, nil
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}
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