}

// figure out the most commonVersions across disk that satisfies
// the 'writeQuorum' this function returns "" if quorum cannot
// be achieved and disks have too many inconsistent versions.
func reduceCommonVersions(diskVersions [][]byte, writeQuorum int) (versions []byte) {
	diskVersionsCount := make(map[uint64]int)
	for _, versions := range diskVersions {
		if len(versions) > 0 {

					UndoWrite:  true,
					OldDataDir: dataDirs[index],
				})
			}, index)
		}
		dg.Wait()
	}
	var dataDir string
	var versions []byte
	if err == nil {
		versions = reduceCommonVersions(diskVersions, writeQuorum)
		for index, dversions := range diskVersions {
			if errs[index] != nil {
				continue
			}
			if !bytes.Equal(dversions, versions) {
				if len(dversions) > len(versions) {