func (s *Snapshot) getRaidMDstat() {
	b, _ := ioutil.ReadFile("/proc/mdstat")
	if i := bytes.IndexByte(b, '\n'); i != -1 && len(b) > i+1 {
		b = b[i+1:]
	}
	s.Raid.MDstat = string(b)
}
getRaidMDstat parses this:
/* four drive raid1:
$ cat /proc/mdstat
Personalities : [raid1] [linear] [multipath] [raid0] [raid6] [raid5] [raid4] [raid10]
md1 : active raid1 sdd2[3] sdb2[1] sdc2[2] sda2[0]
536738816 blocks super 1.2 [4/4] [UUUU]
bitmap: 3/4 pages [12KB], 65536KB chunk
unused devices: <none>.
package snapshot
import (
	"bytes"
	"context"
	"io/ioutil"
	"os/exec"
	"strings"
)
func (s *Snapshot) getRaidData(ctx context.Context, useSudo, run bool) error {
	if !run {
		return nil
	}
	s.Raid = &RaidData{}
	s.getRaidMDstat()
	return s.getRaidMegaCLI(ctx, useSudo)
}