type ObjectLayer interface {
	// Locking operations on object.
	NewNSLock(bucket string, objects ...string) RWLocker

	// Storage operations.
	Shutdown(context.Context) error
	NSScanner(ctx context.Context, updates chan<- DataUsageInfo, wantCycle uint32, scanMode madmin.HealScanMode) error
	BackendInfo() madmin.BackendInfo
	Legacy() bool // Only returns true for deployments which use CRCMOD as its object distribution algorithm.

	for i := range errs {
		errs[i] = errDiskOngoingReq
	}

	done := make(chan bool, er.setDriveCount)
	disks := er.getDisks()

	ropts := ReadOptions{
		ReadData:         readData,
		InclFreeVersions: opts.InclFreeVersions,
		Healing:          false,
	}

	mrfCheck := make(chan FileInfo)
	defer xioutil.SafeClose(mrfCheck)

	var rw sync.Mutex

	// Ask for all disks first;

			if disk == nil || !disk.IsOnline() {
				parityDrives++
				offlineDrives++
				continue
			}
		}

		if offlineDrives >= (len(onlineDisks)+1)/2 {
			// if offline drives are more than 50% of the drives
			// we have no quorum, we shouldn't proceed just
			// fail at that point.
			return nil, toObjectErr(errErasureWriteQuorum, bucket, object)
		}

		if parityDrives >= len(onlineDisks)/2 {

			if !srcTimestamp.IsZero() {
				ondiskTimestamp, err := time.Parse(time.RFC3339Nano, lastTaggingTimestamp)
				// update tagging metadata only if replica  timestamp is newer than what's on disk
				if err != nil || (err == nil && !ondiskTimestamp.After(srcTimestamp)) {
					srcInfo.UserDefined[ReservedMetadataPrefixLower+TaggingTimestamp] = srcTimestamp.UTC().Format(time.RFC3339Nano)