if err not nil, that shouldn't add the result into location.volumes[], because store.Join() will report all volumes infomation to master, includes volumes size: func (v *Volume) Size() int64 { v.accessLock.Lock() defer v.accessLock.Unlock()

    // but here dataFile is nil, it will panic
    stat, e := v.dataFile.Stat()
    if e == nil {
            return stat.Size()
    }
    log.Printf("Failed to read file size %s %s\n", v.dataFile.Name(),

e.Error()) return -1 }

Thanks! This is nice and solid.