maxmustermann/minio
1
0
Fork 0
Code Issues Pull requests Projects Releases Wiki Activity

[feature] allow for an odd number of erasure packs (#9221)

Browse source 
Too many deployments come up with an odd number
of hosts or drives, to facilitate even distribution
among those setups allow for odd and prime numbers
based packs.
This commit is contained in:
Harshavardhana 2020-03-31 09:32:16 -07:00 committed by GitHub
parent 90c365a174
commit 30707659b5
No known key found for this signature in database
GPG key ID: 4AEE18F83AFDEB23
15 changed files with 74 additions and 299 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

4
cmd/endpoint-ellipses.go
View file

@ -40,7 +40,7 @@ type endpointSet struct {
// Supported set sizes this is used to find the optimal
// single set size.
var setSizes = []uint64{4, 6, 8, 10, 12, 14, 16}
var setSizes = []uint64{4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16}
// getDivisibleSize - returns a greatest common divisor of
// all the ellipses sizes.
@ -60,7 +60,7 @@ func getDivisibleSize(totalSizes []uint64) (result uint64) {
// isValidSetSize - checks whether given count is a valid set size for erasure coding.
var isValidSetSize = func(count uint64) bool {
return (count >= setSizes[0] && count <= setSizes[len(setSizes)-1] && count%2 == 0)
return (count >= setSizes[0] && count <= setSizes[len(setSizes)-1])
}
// getSetIndexes returns list of indexes which provides the set size

41
cmd/endpoint-ellipses_test.go
View file

@ -130,9 +130,9 @@ func TestGetSetIndexesEnvOverride(t *testing.T) {
{
[]string{"http://host{1...11}/data{1...11}"},
[]uint64{121},
nil,
[][]uint64{{11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11}},
11,
false,
true,
},
{
[]string{"data{1...60}"},
@ -183,12 +183,6 @@ func TestGetSetIndexes(t *testing.T) {
success bool
}{
// Invalid inputs.
{
[]string{"data{1...27}"},
[]uint64{27},
nil,
false,
},
{
[]string{"data{1...3}"},
[]uint64{3},
@ -202,6 +196,12 @@ func TestGetSetIndexes(t *testing.T) {
false,
},
// Valid inputs.
{
[]string{"data{1...27}"},
[]uint64{27},
[][]uint64{{9, 9, 9}},
true,
},
{
[]string{"data/controller1/export{1...4}, data/controller2/export{1...8}, data/controller3/export{1...12}"},
[]uint64{4, 8, 12},
@ -223,7 +223,7 @@ func TestGetSetIndexes(t *testing.T) {
{
[]string{"data/controller{1...11}/export{1...8}"},
[]uint64{88},
[][]uint64{{8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8}},
[][]uint64{{11, 11, 11, 11, 11, 11, 11, 11}},
true,
},
{
@ -292,12 +292,6 @@ func TestParseEndpointSet(t *testing.T) {
endpointSet{},
false,
},
// Indivisible range.
{
"{1...27}",
endpointSet{},
false,
},
// No range specified.
{
"{...}",
@ -323,6 +317,23 @@ func TestParseEndpointSet(t *testing.T) {
false,
},
// Tests valid inputs.
{
"{1...27}",
endpointSet{
[]ellipses.ArgPattern{
[]ellipses.Pattern{
{
Prefix: "",
Suffix: "",
Seq: getSequences(1, 27, 0),
},
},
},
nil,
[][]uint64{{9, 9, 9}},
},
true,
},
{
"/export/set{1...64}",
endpointSet{

2
cmd/format-xl.go
View file

@ -705,7 +705,7 @@ func saveFormatXLAll(ctx context.Context, storageDisks []StorageAPI, formats []*
}, index)
}
writeQuorum := len(storageDisks)/2 + 1
writeQuorum := getWriteQuorum(len(storageDisks))
// Wait for the routines to finish.
return reduceWriteQuorumErrs(ctx, g.Wait(), nil, writeQuorum)
}

16
cmd/utils.go
View file

@ -93,6 +93,22 @@ func path2BucketObject(s string) (bucket, prefix string) {
return path2BucketObjectWithBasePath("", s)
}
func getDefaultParityBlocks(drive int) int {
return drive / 2
}
func getDefaultDataBlocks(drive int) int {
return drive - getDefaultParityBlocks(drive)
}
func getReadQuorum(drive int) int {
return getDefaultDataBlocks(drive)
}
func getWriteQuorum(drive int) int {
return getDefaultDataBlocks(drive) + 1
}
// URI scheme constants.
const (
httpScheme = "http"

6
cmd/xl-v1-bucket.go
View file

@ -65,7 +65,7 @@ func (xl xlObjects) MakeBucketWithLocation(ctx context.Context, bucket, location
}, index)
}
writeQuorum := len(storageDisks)/2 + 1
writeQuorum := getWriteQuorum(len(storageDisks))
err := reduceWriteQuorumErrs(ctx, g.Wait(), bucketOpIgnoredErrs, writeQuorum)
if err == errXLWriteQuorum {
// Purge successfully created buckets if we don't have writeQuorum.
@ -136,7 +136,7 @@ func (xl xlObjects) getBucketInfo(ctx context.Context, bucketName string) (bucke
// reduce to one error based on read quorum.
// `nil` is deliberately passed for ignoredErrs
// because these errors were already ignored.
readQuorum := len(xl.getDisks()) / 2
readQuorum := getReadQuorum(len(xl.getDisks()))
return BucketInfo{}, reduceReadQuorumErrs(ctx, bucketErrs, nil, readQuorum)
}
@ -259,7 +259,7 @@ func (xl xlObjects) DeleteBucket(ctx context.Context, bucket string, forceDelete
return nil
}
writeQuorum := len(storageDisks)/2 + 1
writeQuorum := getWriteQuorum(len(storageDisks))
err := reduceWriteQuorumErrs(ctx, dErrs, bucketOpIgnoredErrs, writeQuorum)
if err == errXLWriteQuorum {
undoDeleteBucket(storageDisks, bucket)

2
cmd/xl-v1-common.go
View file

@ -81,7 +81,7 @@ func (xl xlObjects) isObject(bucket, prefix string) (ok bool) {
// quorum intentionally, but rely on the default case scenario. Actual quorum
// verification will happen by top layer by using getObjectInfo() and will be
// ignored if necessary.
readQuorum := len(storageDisks) / 2
readQuorum := getReadQuorum(len(storageDisks))
return reduceReadQuorumErrs(context.Background(), g.Wait(), objectOpIgnoredErrs, readQuorum) == nil
}

16
cmd/xl-v1-healing.go
View file

@ -46,7 +46,7 @@ func (xl xlObjects) HealBucket(ctx context.Context, bucket string, dryRun, remov
storageDisks := xl.getDisks()
// get write quorum for an object
writeQuorum := len(storageDisks)/2 + 1
writeQuorum := getWriteQuorum(len(storageDisks))
// Heal bucket.
return healBucket(ctx, storageDisks, bucket, writeQuorum, dryRun)
@ -314,7 +314,7 @@ func (xl xlObjects) healObject(ctx context.Context, bucket string, object string
if m, ok := isObjectDangling(partsMetadata, errs, dataErrs); ok {
writeQuorum := m.Erasure.DataBlocks + 1
if m.Erasure.DataBlocks == 0 {
writeQuorum = len(storageDisks)/2 + 1
writeQuorum = getWriteQuorum(len(storageDisks))
}
if !dryRun && remove {
err = xl.deleteObject(ctx, bucket, object, writeQuorum, false)
@ -492,8 +492,8 @@ func (xl xlObjects) healObjectDir(ctx context.Context, bucket, object string, dr
Bucket: bucket,
Object: object,
DiskCount: len(storageDisks),
ParityBlocks: len(storageDisks) / 2,
DataBlocks: len(storageDisks) / 2,
ParityBlocks: getDefaultParityBlocks(len(storageDisks)),
DataBlocks: getDefaultDataBlocks(len(storageDisks)),
ObjectSize: 0,
}
@ -601,8 +601,8 @@ func defaultHealResult(latestXLMeta xlMetaV1, storageDisks []StorageAPI, errs []
if !latestXLMeta.IsValid() {
// Default to most common configuration for erasure blocks.
result.ParityBlocks = len(storageDisks) / 2
result.DataBlocks = len(storageDisks) / 2
result.ParityBlocks = getDefaultParityBlocks(len(storageDisks))
result.DataBlocks = getDefaultDataBlocks(len(storageDisks))
} else {
result.ParityBlocks = latestXLMeta.Erasure.ParityBlocks
result.DataBlocks = latestXLMeta.Erasure.DataBlocks
@ -729,7 +729,7 @@ func (xl xlObjects) HealObject(ctx context.Context, bucket, object string, opts
if m, ok := isObjectDangling(partsMetadata, errs, []error{}); ok {
writeQuorum := m.Erasure.DataBlocks + 1
if m.Erasure.DataBlocks == 0 {
writeQuorum = len(xl.getDisks())/2 + 1
writeQuorum = getWriteQuorum(len(storageDisks))
}
if !opts.DryRun && opts.Remove {
xl.deleteObject(healCtx, bucket, object, writeQuorum, false)
@ -758,7 +758,7 @@ func (xl xlObjects) HealObject(ctx context.Context, bucket, object string, opts
if m, ok := isObjectDangling(partsMetadata, errs, []error{}); ok {
writeQuorum := m.Erasure.DataBlocks + 1
if m.Erasure.DataBlocks == 0 {
writeQuorum = len(storageDisks)/2 + 1
writeQuorum = getWriteQuorum(len(storageDisks))
}
if !opts.DryRun && opts.Remove {
xl.deleteObject(ctx, bucket, object, writeQuorum, false)

55
cmd/xl-v1-metadata.go
View file

@ -377,61 +377,6 @@ func pickValidXLMeta(ctx context.Context, metaArr []xlMetaV1, modTime time.Time,
// list of all errors that can be ignored in a metadata operation.
var objMetadataOpIgnoredErrs = append(baseIgnoredErrs, errDiskAccessDenied, errVolumeNotFound, errFileNotFound, errFileAccessDenied, errCorruptedFormat)
// readXLMetaParts - returns the XL Metadata Parts from xl.json of one of the disks picked at random.
func (xl xlObjects) readXLMetaParts(ctx context.Context, bucket, object string) (xlMetaParts []ObjectPartInfo, xlMeta map[string]string, err error) {
var ignoredErrs []error
for _, disk := range xl.getLoadBalancedDisks() {
if disk == nil {
ignoredErrs = append(ignoredErrs, errDiskNotFound)
continue
}
xlMetaParts, xlMeta, err = readXLMetaParts(ctx, disk, bucket, object)
if err == nil {
return xlMetaParts, xlMeta, nil
}
// For any reason disk or bucket is not available continue
// and read from other disks.
if IsErrIgnored(err, objMetadataOpIgnoredErrs...) {
ignoredErrs = append(ignoredErrs, err)
continue
}
// Error is not ignored, return right here.
return nil, nil, err
}
// If all errors were ignored, reduce to maximal occurrence
// based on the read quorum.
readQuorum := len(xl.getDisks()) / 2
return nil, nil, reduceReadQuorumErrs(ctx, ignoredErrs, nil, readQuorum)
}
// readXLMetaStat - return xlMetaV1.Stat and xlMetaV1.Meta from one of the disks picked at random.
func (xl xlObjects) readXLMetaStat(ctx context.Context, bucket, object string) (xlStat statInfo, xlMeta map[string]string, err error) {
var ignoredErrs []error
for _, disk := range xl.getLoadBalancedDisks() {
if disk == nil {
ignoredErrs = append(ignoredErrs, errDiskNotFound)
continue
}
// parses only xlMetaV1.Meta and xlMeta.Stat
xlStat, xlMeta, err = readXLMetaStat(ctx, disk, bucket, object)
if err == nil {
return xlStat, xlMeta, nil
}
// For any reason disk or bucket is not available continue
// and read from other disks.
if IsErrIgnored(err, objMetadataOpIgnoredErrs...) {
ignoredErrs = append(ignoredErrs, err)
continue
}
// Error is not ignored, return right here.
return statInfo{}, nil, err
}
// If all errors were ignored, reduce to maximal occurrence
// based on the read quorum.
readQuorum := len(xl.getDisks()) / 2
return statInfo{}, nil, reduceReadQuorumErrs(ctx, ignoredErrs, nil, readQuorum)
}
// writeXLMetadata - writes `xl.json` to a single disk.
func writeXLMetadata(ctx context.Context, disk StorageAPI, bucket, prefix string, xlMeta xlMetaV1) error {
jsonFile := path.Join(prefix, xlMetaJSONFile)

163
cmd/xl-v1-metadata_test.go
View file

@ -17,10 +17,7 @@
package cmd
import (
"bytes"
"context"
"os"
"path"
"testing"
"time"
@ -29,166 +26,6 @@ import (
const ActualSize = 1000
// Tests for reading XL object info.
func TestXLReadStat(t *testing.T) {
ExecObjectLayerDiskAlteredTest(t, testXLReadStat)
}
func testXLReadStat(obj ObjectLayer, instanceType string, disks []string, t *testing.T) {
// Setup for the tests.
bucketName := getRandomBucketName()
objectName := "test-object"
// create bucket.
err := obj.MakeBucketWithLocation(context.Background(), bucketName, "")
// Stop the test if creation of the bucket fails.
if err != nil {
t.Fatalf("%s : %s", instanceType, err.Error())
}
// set of byte data for PutObject.
// object has to be created before running tests for GetObject.
// this is required even to assert the GetObject data,
// since dataInserted === dataFetched back is a primary criteria for any object storage this assertion is critical.
bytesData := []struct {
byteData []byte
}{
{generateBytesData(6 * humanize.MiByte)},
}
// set of inputs for uploading the objects before tests for downloading is done.
putObjectInputs := []struct {
bucketName string
objectName string
contentLength int64
textData []byte
metaData map[string]string
}{
// case - 1.
{bucketName, objectName, int64(len(bytesData[0].byteData)), bytesData[0].byteData, make(map[string]string)},
}
// iterate through the above set of inputs and upkoad the object.
for i, input := range putObjectInputs {
// uploading the object.
_, err = obj.PutObject(context.Background(), input.bucketName, input.objectName, mustGetPutObjReader(t, bytes.NewBuffer(input.textData), input.contentLength, input.metaData["etag"], ""), ObjectOptions{UserDefined: input.metaData})
// if object upload fails stop the test.
if err != nil {
t.Fatalf("Put Object case %d: Error uploading object: <ERROR> %v", i+1, err)
}
}
z := obj.(*xlZones)
xl := z.zones[0].sets[0]
_, _, err = xl.readXLMetaStat(context.Background(), bucketName, objectName)
if err != nil {
t.Fatal(err)
}
// Remove one disk.
removeDiskN(disks, 7)
// Removing disk shouldn't affect reading object info.
_, _, err = xl.readXLMetaStat(context.Background(), bucketName, objectName)
if err != nil {
t.Fatal(err)
}
for _, disk := range disks {
os.RemoveAll(path.Join(disk, bucketName))
}
_, _, err = xl.readXLMetaStat(context.Background(), bucketName, objectName)
if err != errVolumeNotFound {
t.Fatal(err)
}
}
// Tests for reading XL meta parts.
func TestXLReadMetaParts(t *testing.T) {
ExecObjectLayerDiskAlteredTest(t, testXLReadMetaParts)
}
// testListObjectParts - Tests validate listing of object parts when disks go offline.
func testXLReadMetaParts(obj ObjectLayer, instanceType string, disks []string, t *testing.T) {
bucketNames := []string{"minio-bucket", "minio-2-bucket"}
objectNames := []string{"minio-object-1.txt"}
uploadIDs := []string{}
var opts ObjectOptions
// bucketnames[0].
// objectNames[0].
// uploadIds [0].
// Create bucket before intiating NewMultipartUpload.
err := obj.MakeBucketWithLocation(context.Background(), bucketNames[0], "")
if err != nil {
// Failed to create newbucket, abort.
t.Fatalf("%s : %s", instanceType, err.Error())
}
// Initiate Multipart Upload on the above created bucket.
uploadID, err := obj.NewMultipartUpload(context.Background(), bucketNames[0], objectNames[0], opts)
if err != nil {
// Failed to create NewMultipartUpload, abort.
t.Fatalf("%s : %s", instanceType, err.Error())
}
uploadIDs = append(uploadIDs, uploadID)
// Create multipart parts.
// Need parts to be uploaded before MultipartLists can be called and tested.
createPartCases := []struct {
bucketName string
objName string
uploadID string
PartID int
inputReaderData string
inputMd5 string
intputDataSize int64
expectedMd5 string
}{
// Case 1-4.
// Creating sequence of parts for same uploadID.
// Used to ensure that the ListMultipartResult produces one output for the four parts uploaded below for the given upload ID.
{bucketNames[0], objectNames[0], uploadIDs[0], 1, "abcd", "e2fc714c4727ee9395f324cd2e7f331f", int64(len("abcd")), "e2fc714c4727ee9395f324cd2e7f331f"},
{bucketNames[0], objectNames[0], uploadIDs[0], 2, "efgh", "1f7690ebdd9b4caf8fab49ca1757bf27", int64(len("efgh")), "1f7690ebdd9b4caf8fab49ca1757bf27"},
{bucketNames[0], objectNames[0], uploadIDs[0], 3, "ijkl", "09a0877d04abf8759f99adec02baf579", int64(len("abcd")), "09a0877d04abf8759f99adec02baf579"},
{bucketNames[0], objectNames[0], uploadIDs[0], 4, "mnop", "e132e96a5ddad6da8b07bba6f6131fef", int64(len("abcd")), "e132e96a5ddad6da8b07bba6f6131fef"},
}
sha256sum := ""
// Iterating over creatPartCases to generate multipart chunks.
for _, testCase := range createPartCases {
_, perr := obj.PutObjectPart(context.Background(), testCase.bucketName, testCase.objName, testCase.uploadID, testCase.PartID, mustGetPutObjReader(t, bytes.NewBufferString(testCase.inputReaderData), testCase.intputDataSize, testCase.inputMd5, sha256sum), opts)
if perr != nil {
t.Fatalf("%s : %s", instanceType, perr)
}
}
z := obj.(*xlZones)
xl := z.zones[0].sets[0]
uploadIDPath := xl.getUploadIDDir(bucketNames[0], objectNames[0], uploadIDs[0])
_, _, err = xl.readXLMetaParts(context.Background(), minioMetaMultipartBucket, uploadIDPath)
if err != nil {
t.Fatal(err)
}
// Remove one disk.
removeDiskN(disks, 7)
// Removing disk shouldn't affect reading object parts info.
_, _, err = xl.readXLMetaParts(context.Background(), minioMetaMultipartBucket, uploadIDPath)
if err != nil {
t.Fatal(err)
}
for _, disk := range disks {
os.RemoveAll(path.Join(disk, bucketNames[0]))
os.RemoveAll(path.Join(disk, minioMetaMultipartBucket, xl.getMultipartSHADir(bucketNames[0], objectNames[0])))
}
_, _, err = xl.readXLMetaParts(context.Background(), minioMetaMultipartBucket, uploadIDPath)
if err != errFileNotFound {
t.Fatal(err)
}
}
// Test xlMetaV1.AddObjectPart()
func TestAddObjectPart(t *testing.T) {
testCases := []struct {

3
cmd/xl-v1-multipart.go
View file

@ -808,7 +808,8 @@ func (xl xlObjects) cleanupStaleMultipartUploadsOnDisk(ctx context.Context, disk
continue
}
if now.Sub(fi.ModTime) > expiry {
xl.deleteObject(ctx, minioMetaMultipartBucket, uploadIDPath, len(xl.getDisks())/2+1, false)
writeQuorum := getWriteQuorum(len(xl.getDisks()))
xl.deleteObject(ctx, minioMetaMultipartBucket, uploadIDPath, writeQuorum, false)
}
}
}

18
cmd/xl-v1-object.go
View file

@ -340,7 +340,7 @@ func (xl xlObjects) getObjectInfoDir(ctx context.Context, bucket, object string)
}, index)
}
readQuorum := len(storageDisks) / 2
readQuorum := getReadQuorum(len(storageDisks))
err := reduceReadQuorumErrs(ctx, g.Wait(), objectOpIgnoredErrs, readQuorum)
return dirObjectInfo(bucket, object, 0, map[string]string{}), err
}
@ -488,7 +488,7 @@ func (xl xlObjects) putObject(ctx context.Context, bucket string, object string,
// Get parity and data drive count based on storage class metadata
parityDrives := globalStorageClass.GetParityForSC(opts.UserDefined[xhttp.AmzStorageClass])
if parityDrives == 0 {
parityDrives = len(storageDisks) / 2
parityDrives = getDefaultParityBlocks(len(storageDisks))
}
dataDrives := len(storageDisks) - parityDrives
@ -842,11 +842,13 @@ func (xl xlObjects) deleteObjects(ctx context.Context, bucket string, objects []
isObjectDirs[i] = HasSuffix(object, SlashSeparator)
}
storageDisks := xl.getDisks()
for i, object := range objects {
if isObjectDirs[i] {
_, err := xl.getObjectInfoDir(ctx, bucket, object)
if err == errXLReadQuorum {
if isObjectDirDangling(statAllDirs(ctx, xl.getDisks(), bucket, object)) {
if isObjectDirDangling(statAllDirs(ctx, storageDisks, bucket, object)) {
// If object is indeed dangling, purge it.
errs[i] = nil
}
@ -868,7 +870,7 @@ func (xl xlObjects) deleteObjects(ctx context.Context, bucket string, objects []
// class for objects which have reduced quorum
// storage class only needs to be honored for
// Read() requests alone which we already do.
writeQuorums[i] = len(xl.getDisks())/2 + 1
writeQuorums[i] = getWriteQuorum(len(storageDisks))
}
return xl.doDeleteObjects(ctx, bucket, objects, errs, writeQuorums, isObjectDirs)
@ -934,10 +936,12 @@ func (xl xlObjects) DeleteObject(ctx context.Context, bucket, object string) (er
var writeQuorum int
var isObjectDir = HasSuffix(object, SlashSeparator)
storageDisks := xl.getDisks()
if isObjectDir {
_, err = xl.getObjectInfoDir(ctx, bucket, object)
if err == errXLReadQuorum {
if isObjectDirDangling(statAllDirs(ctx, xl.getDisks(), bucket, object)) {
if isObjectDirDangling(statAllDirs(ctx, storageDisks, bucket, object)) {
// If object is indeed dangling, purge it.
err = nil
}
@ -948,10 +952,10 @@ func (xl xlObjects) DeleteObject(ctx context.Context, bucket, object string) (er
}
if isObjectDir {
writeQuorum = len(xl.getDisks())/2 + 1
writeQuorum = getWriteQuorum(len(storageDisks))
} else {
// Read metadata associated with the object from all disks.
partsMetadata, errs := readAllXLMetadata(ctx, xl.getDisks(), bucket, object)
partsMetadata, errs := readAllXLMetadata(ctx, storageDisks, bucket, object)
// get Quorum for this object
_, writeQuorum, err = objectQuorumFromMeta(ctx, xl, partsMetadata, errs)
if err != nil {

38
cmd/xl-v1-utils.go
View file

@ -122,44 +122,6 @@ func xlMetaV1UnmarshalJSON(ctx context.Context, xlMetaBuf []byte) (xlMeta xlMeta
return xlMeta, err
}
// read xl.json from the given disk, parse and return xlV1MetaV1.Parts.
func readXLMetaParts(ctx context.Context, disk StorageAPI, bucket string, object string) ([]ObjectPartInfo, map[string]string, error) {
// Reads entire `xl.json`.
xlMetaBuf, err := disk.ReadAll(bucket, path.Join(object, xlMetaJSONFile))
if err != nil {
logger.LogIf(ctx, err)
return nil, nil, err
}
var xlMeta xlMetaV1
xlMeta, err = xlMetaV1UnmarshalJSON(ctx, xlMetaBuf)
if err != nil {
return nil, nil, err
}
return xlMeta.Parts, xlMeta.Meta, nil
}
// read xl.json from the given disk and parse xlV1Meta.Stat and xlV1Meta.Meta using jsoniter.
func readXLMetaStat(ctx context.Context, disk StorageAPI, bucket string, object string) (si statInfo,
mp map[string]string, e error) {
// Reads entire `xl.json`.
xlMetaBuf, err := disk.ReadAll(bucket, path.Join(object, xlMetaJSONFile))
if err != nil {
logger.LogIf(ctx, err)
return si, nil, err
}
var xlMeta xlMetaV1
xlMeta, err = xlMetaV1UnmarshalJSON(ctx, xlMetaBuf)
if err != nil {
return si, mp, err
}
// Return structured `xl.json`.
return xlMeta.Stat, xlMeta.Meta, nil
}
// readXLMeta reads `xl.json` and returns back XL metadata structure.
func readXLMeta(ctx context.Context, disk StorageAPI, bucket string, object string) (xlMeta xlMetaV1, err error) {
// Reads entire `xl.json`.

2
docs/distributed/DESIGN.md
View file

@ -42,7 +42,7 @@ Expansion of ellipses and choice of erasure sets based on this expansion is an a
- We limited the number of drives to 16 for erasure set because, erasure code shards more than 16 can become chatty and do not have any performance advantages. Additionally since 16 drive erasure set gives you tolerance of 8 disks per object by default which is plenty in any practical scenario.
- Choice of erasure set size is automatic based on the number of disks available, let's say for example if there are 32 servers and 32 disks which is a total of 1024 disks. In this scenario 16 becomes the erasure set size. This is decided based on the greatest common divisor (GCD) of acceptable erasure set sizes ranging from *4, 6, 8, 10, 12, 14, 16*.
- Choice of erasure set size is automatic based on the number of disks available, let's say for example if there are 32 servers and 32 disks which is a total of 1024 disks. In this scenario 16 becomes the erasure set size. This is decided based on the greatest common divisor (GCD) of acceptable erasure set sizes ranging from *4 to 16*.
- *If total disks has many common divisors the algorithm chooses the minimum amounts of erasure sets possible for a erasure set size of any N*. In the example with 1024 disks - 4, 8, 16 are GCD factors. With 16 disks we get a total of 64 possible sets, with 8 disks we get a total of 128 possible sets, with 4 disks we get a total of 256 possible sets. So algorithm automatically chooses 64 sets, which is *16 * 64 = 1024* disks in total.

2
docs/distributed/README.md
View file

@ -37,7 +37,7 @@ To start a distributed MinIO instance, you just need to pass drive locations as
__NOTE:__
- All the nodes running distributed MinIO need to have same access key and secret key for the nodes to connect. To achieve this, it is __recommended__ to export access key and secret key as environment variables, `MINIO_ACCESS_KEY` and `MINIO_SECRET_KEY`, on all the nodes before executing MinIO server command.
- __MinIO creates erasure-coding sets of 4, 6, 8, 10, 12, 14 or 16 drives. The number of drives you provide must be a multiple of one of those numbers.__
- __MinIO creates erasure-coding sets of *4* to *16* drives. The number of drives you provide must be a multiple of one of those numbers.__
- __MinIO chooses the largest EC set size which divides into the total number of drives given. For example, 8 drives will be used as a single EC set of size 8, not two sets of size 4.__
- __Each object is written to a single EC set, and therefore is spread over no more than 16 drives.__
- __All the nodes running distributed MinIO setup are recommended to be homogeneous, i.e. same operating system, same number of disks and same network interconnects.__

5
pkg/dsync/drwmutex.go
View file

@ -20,7 +20,6 @@ import (
"context"
"errors"
golog "log"
"math"
"math/rand"
"os"
"sync"
@ -237,8 +236,8 @@ func lock(ds *Dsync, locks *[]string, id, source string, isReadLock bool, lockNa
done := false
timeout := time.After(DRWMutexAcquireTimeout)
dquorum := int(len(restClnts)/2) + 1
dquorumReads := int(math.Ceil(float64(len(restClnts)) / 2.0))
dquorumReads := (len(restClnts) + 1) / 2
dquorum := dquorumReads + 1
for ; i < len(restClnts); i++ { // Loop until we acquired all locks