Synology NAS – Add disk and include in md0+md1

Adding new disks, including in mirroring of system partitions (md0 and md1)

GNU parted documentation

  1. Add the new disks as hot spare, then remove them (will create the disklabel, otherwise just do this using parted)
  2. Check the partition table of a disk already used for system and swap. Find it by checking mdstat (cat /proc/mdstat)
    # cat /proc/mdstat
    Personalities : [linear] [raid0] [raid1] [raid10] [raid6] [raid5] [raid4]
    md1 : active raid1 sdd2[3] sdb2[1] sdc2[2] sda2[0]
    2097088 blocks [5/4] [UUUU_]
    
    md0 : active raid1 sdd1[3] sdb1[1] sda1[0] sdc1[2]
    2490176 blocks [5/4] [UUUU_]
    
    unused devices:
    
    # parted /dev/sda
    (parted) unit s
    (parted) p
    Model: ATA ST3000DM001-1CH1 (scsi)
    Disk /dev/sda: 5860533168s
    Sector size (logical/physical): 512B/512B
    Partition Table: gpt
    Disk Flags:
    
    Number Start End Size File system Name Flags
    1 2048s 4982527s 4980480s ext4 raid
    2 4982528s 9176831s 4194304s linux-swap(v1) raid
    
    (parted) q
    
  3. Run parted on the new disk
    # parted /dev/sde
    (parted) unit s
    (parted) p
    Model: ATA ST3000DM001-1CH1 (scsi)
    Disk /dev/sda: 5860533168s
    Sector size (logical/physical): 512B/512B
    Partition Table: gpt
    Disk Flags:
    
    Number Start End Size File system Name Flags
    
    (parted) mkpart system ext4 2048 4982527
    (parted) mkpart swap linux-swap 4982528 9176831
    (parted) p
    ...
    Number Start End Size File system Name Flags
    1 2048s 4982527s 4980480s ext4 system
    2 4982528s 9176831s 4194304s linux-swap(v1) swap
    (parted) q
    
  4. Add partitions to system and swap
    # mdadm --add /dev/md0 /dev/sde1
    # mdadm --add /dev/md1 /dev/sde2
    
  5. Check rebuild status using ‘cat /proc/mdstat’
  6. Final result should be something like:
    
    # cat /proc/mdstat
    Personalities : [linear] [raid0] [raid1] [raid10] [raid6] [raid5] [raid4]
    md1 : active raid1 sde2[4] sdd2[3] sdb2[1] sdc2[2] sda2[0]
    2097088 blocks [5/5] [UUUUU]
    
    md0 : active raid1 sde1[4] sdd1[3] sdb1[1] sda1[0] sdc1[2]
    2490176 blocks [5/5] [UUUUU]
    
    unused devices: