var (
	ODirectPoolLarge = sync.Pool{
		New: func() interface{} {
			b := disk.AlignedBlock(LargeBlock)
			return &b
		},
	}
	ODirectPoolMedium = sync.Pool{
		New: func() interface{} {
			b := disk.AlignedBlock(MediumBlock)
			return &b
		},
	}
	ODirectPoolSmall = sync.Pool{
		New: func() interface{} {
			b := disk.AlignedBlock(SmallBlock)
			return &b
		},
	}
)

	xlStorageFormatFile = "xl.meta"

	// XL metadata file backup file carries previous per object metadata.
	xlStorageFormatFileBackup = "xl.meta.bkp"
)

var alignedBuf []byte

func init() {
	alignedBuf = disk.AlignedBlock(xioutil.DirectioAlignSize)
	_, _ = rand.Read(alignedBuf)
}

// isValidVolname verifies a volname name in accordance with object
// layer requirements.
func isValidVolname(volname string) bool {