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minio/cmd/prepare-storage.go

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/*
* 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 cmd
import (
"fmt"
"time"
"github.com/minio/minio/pkg/errors"
)
/*
Following table lists different possible states the backend could be in.
* In a single-node, multi-disk setup, "Online" would refer to disks' status.
* In a multi-node setup, it could refer to disks' or network connectivity
between the nodes, or both.
+----------+--------------------------+-----------------------+
| Online | Format status | Course of action |
| | | |
-----------+--------------------------+-----------------------+
| All | All Formatted | |
+----------+--------------------------+ initObjectLayer |
| Quorum | Quorum Formatted | |
+----------+--------------------------+-----------------------+
| All | Quorum | Print message saying |
| | Formatted, | "Heal via control" |
| | some unformatted | and initObjectLayer |
+----------+--------------------------+-----------------------+
| All | None Formatted | FormatDisks |
| | | and initObjectLayer |
| | | |
+----------+--------------------------+-----------------------+
| No | | Wait till enough |
| Quorum | _ | nodes are online and |
| | | one of the above |
| | | sections apply |
+----------+--------------------------+-----------------------+
| | | |
| Quorum | Quorum UnFormatted | Abort |
+----------+--------------------------+-----------------------+
A disk can be in one of the following states.
- Unformatted
- Formatted
- Corrupted
- Offline
*/
// InitActions - a type synonym for enumerating initialization activities.
type InitActions int
const (
// FormatDisks - see above table for disk states where it is applicable.
FormatDisks InitActions = iota
// SuggestToHeal - Prints heal message and initialize object layer.
SuggestToHeal
// WaitForQuorum - Wait for quorum number of disks to be online.
WaitForQuorum
// WaitForAll - Wait for all disks to be online.
WaitForAll
// WaitForFormatting - Wait for formatting to be triggered
// from the '1st' server in the cluster.
WaitForFormatting
// WaitForConfig - Wait for all servers to have the same config
// including (credentials, version and time).
WaitForConfig
// InitObjectLayer - Initialize object layer.
InitObjectLayer
// Abort initialization of object layer since there aren't enough good
// copies of format.json to recover.
Abort
)
// configErrs contains the list of configuration errors.
var configErrs = []error{
errInvalidAccessKeyID,
errAuthentication,
errServerVersionMismatch,
errServerTimeMismatch,
}
// Quick error to actions converts looking for specific errors
// which need to be returned quickly and server should wait instead.
func quickErrToActions(errMap map[error]int) InitActions {
var action InitActions
for _, configErr := range configErrs {
if errMap[configErr] > 0 {
action = WaitForConfig
break
}
}
return action
}
// reduceInitXLErrs reduces errors found in distributed XL initialization
func reduceInitXLErrs(storageDisks []StorageAPI, sErrs []error) error {
var foundErrs int
for i := range sErrs {
if sErrs[i] != nil {
foundErrs++
}
}
if foundErrs == 0 {
return nil
}
// Early quit if there is a config error
for i := range sErrs {
if contains(configErrs, sErrs[i]) {
return fmt.Errorf("%s: %s", storageDisks[i], sErrs[i])
}
}
// Combine all disk errors otherwise for user inspection
return fmt.Errorf("%s", combineDiskErrs(storageDisks, sErrs))
}
// Preparatory initialization stage for XL validates known errors.
// Converts them into specific actions. These actions have special purpose
// which caller decides on what needs to be done.
// Logic used in this function is as shown below.
//
// ---- Possible states and handled conditions -----
//
// - Formatted setup
// - InitObjectLayer when `disksFormatted >= readQuorum`
// - Wait for quorum when `disksFormatted < readQuorum && disksFormatted + disksOffline >= readQuorum`
// (we don't know yet if there are unformatted disks)
// - Wait for heal when `disksFormatted >= readQuorum && disksUnformatted > 0`
// (here we know there is at least one unformatted disk which requires healing)
//
// - Unformatted setup
// - Format/Wait for format when `disksUnformatted == diskCount`
//
// - Wait for all when `disksUnformatted + disksFormatted + diskOffline == diskCount`
//
// Under all other conditions should lead to server initialization aborted.
func prepForInitXL(firstDisk bool, sErrs []error, diskCount int) InitActions {
// Count errors by error value.
errMap := make(map[error]int)
for _, err := range sErrs {
errMap[errors.Cause(err)]++
}
// Validates and converts specific config errors into WaitForConfig.
if quickErrToActions(errMap) == WaitForConfig {
return WaitForConfig
}
readQuorum := diskCount / 2
disksOffline := errMap[errDiskNotFound]
disksFormatted := errMap[nil]
disksUnformatted := errMap[errUnformattedDisk]
// No Quorum lots of offline disks, wait for quorum.
if disksOffline > readQuorum {
return WaitForQuorum
}
// All disks are unformatted, proceed to formatting disks.
if disksUnformatted == diskCount {
// Only the first server formats an uninitialized setup, others wait for notification.
if firstDisk { // First node always initializes.
return FormatDisks
}
return WaitForFormatting
}
// Already formatted and in quorum, proceed to initialization of object layer.
if disksFormatted >= readQuorum {
if disksFormatted+disksOffline == diskCount {
return InitObjectLayer
}
// Some of the formatted disks are possibly corrupted or unformatted,
// let user know to heal them.
return SuggestToHeal
}
// Some unformatted, some disks formatted and some disks are offline but we don't
// quorum to decide. This is an undecisive state - wait for all of offline disks
// to be online to figure out the course of action.
if disksUnformatted+disksFormatted+disksOffline == diskCount {
return WaitForAll
}
// Exhausted all our checks, un-handled situations such as some disks corrupted we Abort.
return Abort
}
// Prints retry message upon a specific retry count.
func printRetryMsg(sErrs []error, storageDisks []StorageAPI) {
for i, sErr := range sErrs {
switch sErr {
case errDiskNotFound, errFaultyDisk, errFaultyRemoteDisk:
errorIf(sErr, "Disk %s is still unreachable", storageDisks[i])
}
}
}
// Maximum retry attempts.
const maxRetryAttempts = 5
// Implements a jitter backoff loop for formatting all disks during
// initialization of the server.
func retryFormattingXLDisks(firstDisk bool, endpoints EndpointList, storageDisks []StorageAPI) error {
if len(endpoints) == 0 {
return errInvalidArgument
}
if storageDisks == nil {
return errInvalidArgument
}
// Done channel is used to close any lingering retry routine, as soon
// as this function returns.
doneCh := make(chan struct{})
// Indicate to our retry routine to exit cleanly, upon this function return.
defer close(doneCh)
// prepare getElapsedTime() to calculate elapsed time since we started trying formatting disks.
// All times are rounded to avoid showing milli, micro and nano seconds
formatStartTime := time.Now().Round(time.Second)
getElapsedTime := func() string {
return time.Now().Round(time.Second).Sub(formatStartTime).String()
}
// Wait on the jitter retry loop.
retryTimerCh := newRetryTimerSimple(doneCh)
for {
select {
case retryCount := <-retryTimerCh:
// Attempt to load all `format.json` from all disks.
formatConfigs, sErrs := loadAllFormats(storageDisks)
if retryCount > maxRetryAttempts {
// After max retry attempts we start printing
// actual errors for disks not being available.
printRetryMsg(sErrs, storageDisks)
}
// Pre-emptively check if one of the formatted disks
// is invalid. This function returns success for the
// most part unless one of the formats is not consistent
// with expected XL format. For example if a user is
// trying to pool FS backend into an XL set.
if index, err := checkFormatXLValues(formatConfigs); err != nil {
// We will perhaps print and retry for the first 5 attempts
// because in XL initialization first server is the one which
// initializes the erasure set. This check ensures that the
// rest of the other servers do get a chance to see that the
// first server has a wrong format and exit gracefully.
// refer - https://github.com/minio/minio/issues/4140
if retryCount > maxRetryAttempts {
errorIf(err, "%s : Detected disk in unexpected format",
storageDisks[index])
continue
}
return err
}
// Check if this is a XL or distributed XL, anything > 1 is considered XL backend.
switch prepForInitXL(firstDisk, sErrs, len(storageDisks)) {
case Abort:
return reduceInitXLErrs(storageDisks, sErrs)
case FormatDisks:
printFormatMsg(endpoints, storageDisks, printOnceFn())
return initFormatXL(storageDisks)
case InitObjectLayer:
// Validate formats loaded before proceeding forward.
err := genericFormatCheckXL(formatConfigs, sErrs)
if err == nil {
printRegularMsg(endpoints, storageDisks, printOnceFn())
}
return err
case SuggestToHeal:
// Validate formats loaded before proceeding forward.
err := genericFormatCheckXL(formatConfigs, sErrs)
if err == nil {
printHealMsg(endpoints, storageDisks, printOnceFn())
}
return err
case WaitForQuorum:
log.Printf(
"Initializing data volume. Waiting for minimum %d servers to come online. (elapsed %s)\n",
len(storageDisks)/2+1, getElapsedTime(),
)
case WaitForConfig:
// Print configuration errors.
return reduceInitXLErrs(storageDisks, sErrs)
case WaitForAll:
log.Printf("Initializing data volume for first time. Waiting for other servers to come online (elapsed %s)\n", getElapsedTime())
case WaitForFormatting:
log.Printf("Initializing data volume for first time. Waiting for first server to come online (elapsed %s)\n", getElapsedTime())
}
case <-globalServiceDoneCh:
return fmt.Errorf("Initializing data volumes gracefully stopped")
}
}
}
// Initialize storage disks based on input arguments.
func initStorageDisks(endpoints EndpointList) ([]StorageAPI, error) {
// Bootstrap disks.
storageDisks := make([]StorageAPI, len(endpoints))
for index, endpoint := range endpoints {
// Intentionally ignore disk not found errors. XL is designed
// to handle these errors internally.
storage, err := newStorageAPI(endpoint)
if err != nil && err != errDiskNotFound {
return nil, err
}
storageDisks[index] = storage
}
return storageDisks, nil
}
// Wrap disks into retryable disks.
func initRetryableStorageDisks(disks []StorageAPI, retryUnit, retryCap, retryInterval time.Duration, retryThreshold int) (outDisks []StorageAPI) {
// Initialize the disk into a retryable-disks wrapper.
outDisks = make([]StorageAPI, len(disks))
for i, disk := range disks {
outDisks[i] = &retryStorage{
remoteStorage: disk,
retryInterval: retryInterval,
maxRetryAttempts: retryThreshold,
retryUnit: retryUnit,
retryCap: retryCap,
offlineTimestamp: UTCNow(), // Set timestamp to prevent immediate marking as offline
}
}
return
}
// Format disks before initialization of object layer.
func waitForFormatXLDisks(firstDisk bool, endpoints EndpointList, storageDisks []StorageAPI) (formattedDisks []StorageAPI, err error) {
if len(endpoints) == 0 {
return nil, errInvalidArgument
}
if storageDisks == nil {
return nil, errInvalidArgument
}
// Retryable disks before formatting, we need to have a larger
// retry window (30 seconds, with once-per-second retries) so
// that we wait enough amount of time before the disks come
// online.
retryDisks := initRetryableStorageDisks(storageDisks, time.Second, time.Second*30,
globalStorageInitHealthCheckInterval, globalStorageInitRetryThreshold)
// Start retry loop retrying until disks are formatted
// properly, until we have reached a conditional quorum of
// formatted disks.
if err = retryFormattingXLDisks(firstDisk, endpoints, retryDisks); err != nil {
return nil, err
}
// Initialize the disk into a formatted disks wrapper. This
// uses a shorter retry window (5ms with once-per-ms retries)
formattedDisks = initRetryableStorageDisks(storageDisks, time.Millisecond, time.Millisecond*5,
globalStorageHealthCheckInterval, globalStorageRetryThreshold)
// Success.
return formattedDisks, nil
}