minio/xl-v1.go
Harshavardhana 3ac39ff107 XL: Change minimum disks supported to 6 now. (#2023)
This change co-incides with another patch set which
reduces the writeQuorum requirement. With the
write quorum change it is now possible to support
6 disk configuration.
2016-06-29 02:05:29 -07:00

221 lines
6.7 KiB
Go

/*
* Minio Cloud Storage, (C) 2016 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 (
"errors"
"fmt"
"sort"
"github.com/minio/minio/pkg/disk"
)
// XL constants.
const (
// Format config file carries backend format specific details.
formatConfigFile = "format.json"
// Format config tmp file carries backend format.
formatConfigFileTmp = "format.json.tmp"
// XL metadata file carries per object metadata.
xlMetaJSONFile = "xl.json"
// Uploads metadata file carries per multipart object metadata.
uploadsJSONFile = "uploads.json"
)
// xlObjects - Implements XL object layer.
type xlObjects struct {
physicalDisks []string // Collection of regular disks.
storageDisks []StorageAPI // Collection of initialized backend disks.
dataBlocks int // dataBlocks count caculated for erasure.
parityBlocks int // parityBlocks count calculated for erasure.
readQuorum int // readQuorum minimum required disks to read data.
writeQuorum int // writeQuorum minimum required disks to write data.
// List pool management.
listPool *treeWalkPool
}
// errXLMaxDisks - returned for reached maximum of disks.
var errXLMaxDisks = errors.New("Number of disks are higher than supported maximum count '16'")
// errXLMinDisks - returned for minimum number of disks.
var errXLMinDisks = errors.New("Number of disks are smaller than supported minimum count '8'")
// errXLNumDisks - returned for odd number of disks.
var errXLNumDisks = errors.New("Number of disks should be multiples of '2'")
// errXLReadQuorum - did not meet read quorum.
var errXLReadQuorum = errors.New("I/O error. did not meet read quorum.")
// errXLWriteQuorum - did not meet write quorum.
var errXLWriteQuorum = errors.New("I/O error. did not meet write quorum.")
// errXLDataCorrupt - err data corrupt.
var errXLDataCorrupt = errors.New("data likely corrupted, all blocks are zero in length")
const (
// Maximum erasure blocks.
maxErasureBlocks = 16
// Minimum erasure blocks.
minErasureBlocks = 6
)
// Validate if input disks are sufficient for initializing XL.
func checkSufficientDisks(disks []string) error {
// Verify total number of disks.
totalDisks := len(disks)
if totalDisks > maxErasureBlocks {
return errXLMaxDisks
}
if totalDisks < minErasureBlocks {
return errXLMinDisks
}
// isEven function to verify if a given number if even.
isEven := func(number int) bool {
return number%2 == 0
}
// Verify if we have even number of disks.
// only combination of 6, 8, 10, 12, 14, 16 are supported.
if !isEven(totalDisks) {
return errXLNumDisks
}
// Success.
return nil
}
// newXLObjects - initialize new xl object layer.
func newXLObjects(disks []string) (ObjectLayer, error) {
// Validate if input disks are sufficient.
if err := checkSufficientDisks(disks); err != nil {
return nil, err
}
// Bootstrap disks.
storageDisks := make([]StorageAPI, len(disks))
for index, disk := range disks {
var err error
// Intentionally ignore disk not found errors. XL will
// manage such errors internally.
storageDisks[index], err = newStorageAPI(disk)
if err != nil && err != errDiskNotFound {
return nil, err
}
}
// Runs house keeping code, like creating minioMetaBucket, cleaning up tmp files etc.
xlHouseKeeping(storageDisks)
// Attempt to load all `format.json`.
formatConfigs, sErrs := loadAllFormats(storageDisks)
// Generic format check validates all necessary cases.
if err := genericFormatCheck(formatConfigs, sErrs); err != nil {
return nil, 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)
}
case errSomeDiskUnformatted:
// All drives online but some report missing format.json.
if err := healFormatXL(storageDisks); err != nil {
// There was an unexpected unrecoverable error during healing.
return nil, fmt.Errorf("Unable to heal backend %s", err)
}
case errSomeDiskOffline:
// Some disks offline but some report missing format.json.
// FIXME.
}
// Load saved XL format.json and validate.
newPosixDisks, err := loadFormatXL(storageDisks)
if err != nil {
// errCorruptedDisk - healing failed
return nil, fmt.Errorf("Unable to recognize backend format, %s", err)
}
// Calculate data and parity blocks.
dataBlocks, parityBlocks := len(newPosixDisks)/2, len(newPosixDisks)/2
// Initialize xl objects.
xl := xlObjects{
physicalDisks: disks,
storageDisks: newPosixDisks,
dataBlocks: dataBlocks,
parityBlocks: parityBlocks,
listPool: newTreeWalkPool(globalLookupTimeout),
}
// Figure out read and write quorum based on number of storage disks.
// Read quorum should be always N/2 + 1 (due to Vandermonde matrix
// erasure requirements)
xl.readQuorum = len(xl.storageDisks)/2 + 1
// Write quorum is assumed if we have total disks + 2
// parity.
xl.writeQuorum = len(xl.storageDisks)/2 + 2
if xl.writeQuorum > len(xl.storageDisks) {
xl.writeQuorum = len(xl.storageDisks)
}
// Return successfully initialized object layer.
return xl, nil
}
// byDiskTotal is a collection satisfying sort.Interface.
type byDiskTotal []disk.Info
func (d byDiskTotal) Len() int { return len(d) }
func (d byDiskTotal) Swap(i, j int) { d[i], d[j] = d[j], d[i] }
func (d byDiskTotal) Less(i, j int) bool {
return d[i].Total < d[j].Total
}
// StorageInfo - returns underlying storage statistics.
func (xl xlObjects) StorageInfo() StorageInfo {
var disksInfo []disk.Info
for _, diskPath := range xl.physicalDisks {
info, err := disk.GetInfo(diskPath)
if err != nil {
errorIf(err, "Unable to fetch disk info for "+diskPath)
continue
}
disksInfo = append(disksInfo, info)
}
// Sort so that the first element is the smallest.
sort.Sort(byDiskTotal(disksInfo))
// Return calculated storage info, choose the lowest Total and
// Free as the total aggregated values. Total capacity is always
// the multiple of smallest disk among the disk list.
return StorageInfo{
Total: disksInfo[0].Total * int64(len(xl.storageDisks)),
Free: disksInfo[0].Free * int64(len(xl.storageDisks)),
}
}