Missing mdam RAID1 array during scan

I have built a new server (Ubuntu 18.04.1) with 4 HDD.

My plan is to use RAID1 overall and came up with this layout after investigation:

sda, sdb four primary partitions (all as fd) with sda1/sdb1 as /boot, sda2/sdb2 as /, sda3/sdb3 as /var and sda4/sdb4 as part of /home

sdc,sdd two primary partitions (all as fd) with sdc1/sdd1 as rest of /home and sdc2/sdd2 to be used as swap.

Currently the swapfile resides in /

~$ ls -lart /swapfile 
-rw------- 1 root root 2147483648 aug 17 08:50 /swapfile

and my expectation is that this swap file should be on md2 (which is missing).

Question is: Can I just create a new array with mdadm and somehow make the OS use that area for swap instead of the swapfile ?

In my first attempts I tried to prepare all configurations during install but failed miserably and in my last attempt I was only setting up /boot and / in the raid configuration and no LVM config.

The planned part worked as expected but somehow a remnant from previous attempts has left me with a missing swap partition.

What I mean is that the mdadm.conf has entry for the swap(besides md0:/boot and md1:/):

ARRAY /dev/md/2  metadata=1.2 UUID=4b13781e:ea3a8209:74173443:77c65a9d name=LOPEZSRV:2

And checking blkid:

~$ sudo blkid
/dev/sdc2: UUID="4b13781e-ea3a-8209-7417-344377c65a9d" UUID_SUB="6ee8ecac-1e75-f5dc-3def-508cba28a512" LABEL="LOPEZSRV:2" TYPE="linux_raid_member" PARTUUID="f260af1c-02"
/dev/sdd2: UUID="4b13781e-ea3a-8209-7417-344377c65a9d" UUID_SUB="3efa76ad-3662-87e6-ed4d-b072cb0e7274" LABEL="LOPEZSRV:2" TYPE="linux_raid_member" PARTUUID="3bce6013-02"

shows them being a member of an array

Also checking the details

~$ sudo mdadm -E /dev/sdc2
/dev/sdc2:
          Magic : a92b4efc
        Version : 1.2
    Feature Map : 0x1
     Array UUID : 4b13781e:ea3a8209:74173443:77c65a9d
           Name : LOPEZSRV:2  (local to host LOPEZSRV)
  Creation Time : Thu Aug 16 14:08:06 2018
     Raid Level : raid1
   Raid Devices : 2

 Avail Dev Size : 3906762752 (1862.89 GiB 2000.26 GB)
     Array Size : 1953381376 (1862.89 GiB 2000.26 GB)
    Data Offset : 264192 sectors
   Super Offset : 8 sectors
   Unused Space : before=264112 sectors, after=18446744073701738496 sectors
          State : active
    Device UUID : 6ee8ecac:1e75f5dc:3def508c:ba28a512

Internal Bitmap : 8 sectors from superblock
    Update Time : Thu Aug 16 14:40:25 2018
  Bad Block Log : 512 entries available at offset 16 sectors
       Checksum : 19220d93 - correct
         Events : 393


   Device Role : Active device 0
   Array State : AA ('A' == active, '.' == missing, 'R' == replacing)

~$ sudo mdadm -E /dev/sdd2
/dev/sdd2:
          Magic : a92b4efc
        Version : 1.2
    Feature Map : 0x1
     Array UUID : 4b13781e:ea3a8209:74173443:77c65a9d
           Name : LOPEZSRV:2  (local to host LOPEZSRV)
  Creation Time : Thu Aug 16 14:08:06 2018
     Raid Level : raid1
   Raid Devices : 2

 Avail Dev Size : 3906762752 (1862.89 GiB 2000.26 GB)
     Array Size : 1953381376 (1862.89 GiB 2000.26 GB)
    Data Offset : 264192 sectors
   Super Offset : 8 sectors
   Unused Space : before=264112 sectors, after=18446744073701738496 sectors
          State : active
    Device UUID : 3efa76ad:366287e6:ed4db072:cb0e7274

Internal Bitmap : 8 sectors from superblock
    Update Time : Thu Aug 16 14:40:25 2018
  Bad Block Log : 512 entries available at offset 16 sectors
       Checksum : 6b6a513d - correct
         Events : 393


   Device Role : Active device 1
   Array State : AA ('A' == active, '.' == missing, 'R' == replacing)

But doing a scan:

~$ sudo mdadm --detail --scan
ARRAY /dev/md/1 metadata=1.2 name=LOPEZSRV:1 UUID=5c7e415a:fe060391:ae611987:474558ec
ARRAY /dev/md/0 metadata=1.2 name=LOPEZSRV:0 UUID=e6a5ed7b:c613d763:e8e6c8a3:8a13ecb1

I only get the arrays for /boot and /

Looking in /proc/mdstat:

~$ cat /proc/mdstat 
Personalities : [raid1] [linear] [multipath] [raid0] [raid6] [raid5] [raid4] [raid10] 
md0 : active raid1 sda1[0] sdb1[1]
      1949696 blocks super 1.2 [2/2] [UU]

md1 : active raid1 sdb2[1] sda2[0]
      97589248 blocks super 1.2 [2/2] [UU]

also only shows the two arrays for /boot and /.

Adding outputs:

~$ sudo mdadm --assemble --scan  --verbose 
mdadm: looking for devices for /dev/md/0
mdadm: No super block found on /dev/md/0 (Expected magic a92b4efc, got 000000ef)
mdadm: no RAID superblock on /dev/md/0
mdadm: No super block found on /dev/md/1 (Expected magic a92b4efc, got 0000040d)
mdadm: no RAID superblock on /dev/md/1
mdadm: /dev/sdd2 has wrong uuid.
mdadm: No super block found on /dev/sdd1 (Expected magic a92b4efc, got 00000000)
mdadm: no RAID superblock on /dev/sdd1
mdadm: No super block found on /dev/sdd (Expected magic a92b4efc, got 00000000)
mdadm: no RAID superblock on /dev/sdd
mdadm: /dev/sdc2 has wrong uuid.
mdadm: No super block found on /dev/sdc1 (Expected magic a92b4efc, got 00000000)
mdadm: no RAID superblock on /dev/sdc1
mdadm: No super block found on /dev/sdc (Expected magic a92b4efc, got 00000000)
mdadm: no RAID superblock on /dev/sdc
mdadm: No super block found on /dev/sdb4 (Expected magic a92b4efc, got 00000000)
mdadm: no RAID superblock on /dev/sdb4
mdadm: No super block found on /dev/sdb3 (Expected magic a92b4efc, got 00000000)
mdadm: no RAID superblock on /dev/sdb3
mdadm: /dev/sdb2 has wrong uuid.
mdadm: /dev/sdb1 is busy - skipping
mdadm: No super block found on /dev/sdb (Expected magic a92b4efc, got a0ddb71c)
mdadm: no RAID superblock on /dev/sdb
mdadm: No super block found on /dev/sda4 (Expected magic a92b4efc, got 00000000)
mdadm: no RAID superblock on /dev/sda4
mdadm: No super block found on /dev/sda3 (Expected magic a92b4efc, got 00000000)
mdadm: no RAID superblock on /dev/sda3
mdadm: /dev/sda2 has wrong uuid.
mdadm: /dev/sda1 is busy - skipping
mdadm: No super block found on /dev/sda (Expected magic a92b4efc, got a0ddb71c)
mdadm: no RAID superblock on /dev/sda
mdadm: cannot open device /dev/sr0: No medium found
mdadm: looking for devices for /dev/md/1
mdadm: No super block found on /dev/md/0 (Expected magic a92b4efc, got 000000ef)
mdadm: no RAID superblock on /dev/md/0
mdadm: No super block found on /dev/md/1 (Expected magic a92b4efc, got 0000040d)
mdadm: no RAID superblock on /dev/md/1
mdadm: /dev/sdd2 has wrong uuid.
mdadm: No super block found on /dev/sdd1 (Expected magic a92b4efc, got 00000000)
mdadm: no RAID superblock on /dev/sdd1
mdadm: No super block found on /dev/sdd (Expected magic a92b4efc, got 00000000)
mdadm: no RAID superblock on /dev/sdd
mdadm: /dev/sdc2 has wrong uuid.
mdadm: No super block found on /dev/sdc1 (Expected magic a92b4efc, got 00000000)
mdadm: no RAID superblock on /dev/sdc1
mdadm: No super block found on /dev/sdc (Expected magic a92b4efc, got 00000000)
mdadm: no RAID superblock on /dev/sdc
mdadm: No super block found on /dev/sdb4 (Expected magic a92b4efc, got 00000000)
mdadm: no RAID superblock on /dev/sdb4
mdadm: No super block found on /dev/sdb3 (Expected magic a92b4efc, got 00000000)
mdadm: no RAID superblock on /dev/sdb3
mdadm: /dev/sdb2 is busy - skipping
mdadm: /dev/sdb1 has wrong uuid.
mdadm: No super block found on /dev/sdb (Expected magic a92b4efc, got a0ddb71c)
mdadm: no RAID superblock on /dev/sdb
mdadm: No super block found on /dev/sda4 (Expected magic a92b4efc, got 00000000)
mdadm: no RAID superblock on /dev/sda4
mdadm: No super block found on /dev/sda3 (Expected magic a92b4efc, got 00000000)
mdadm: no RAID superblock on /dev/sda3
mdadm: /dev/sda2 is busy - skipping
mdadm: /dev/sda1 has wrong uuid.
mdadm: No super block found on /dev/sda (Expected magic a92b4efc, got a0ddb71c)
mdadm: no RAID superblock on /dev/sda
mdadm: cannot open device /dev/sr0: No medium found
mdadm: looking for devices for /dev/md/2
mdadm: No super block found on /dev/md/0 (Expected magic a92b4efc, got 000000ef)
mdadm: no RAID superblock on /dev/md/0
mdadm: No super block found on /dev/md/1 (Expected magic a92b4efc, got 0000040d)
mdadm: no RAID superblock on /dev/md/1
mdadm: No super block found on /dev/sdd1 (Expected magic a92b4efc, got 00000000)
mdadm: no RAID superblock on /dev/sdd1
mdadm: No super block found on /dev/sdd (Expected magic a92b4efc, got 00000000)
mdadm: no RAID superblock on /dev/sdd
mdadm: No super block found on /dev/sdc1 (Expected magic a92b4efc, got 00000000)
mdadm: no RAID superblock on /dev/sdc1
mdadm: No super block found on /dev/sdc (Expected magic a92b4efc, got 00000000)
mdadm: no RAID superblock on /dev/sdc
mdadm: No super block found on /dev/sdb4 (Expected magic a92b4efc, got 00000000)
mdadm: no RAID superblock on /dev/sdb4
mdadm: No super block found on /dev/sdb3 (Expected magic a92b4efc, got 00000000)
mdadm: no RAID superblock on /dev/sdb3
mdadm: /dev/sdb2 has wrong uuid.
mdadm: /dev/sdb1 has wrong uuid.
mdadm: No super block found on /dev/sdb (Expected magic a92b4efc, got a0ddb71c)
mdadm: no RAID superblock on /dev/sdb
mdadm: No super block found on /dev/sda4 (Expected magic a92b4efc, got 00000000)
mdadm: no RAID superblock on /dev/sda4
mdadm: No super block found on /dev/sda3 (Expected magic a92b4efc, got 00000000)
mdadm: no RAID superblock on /dev/sda3
mdadm: /dev/sda2 has wrong uuid.
mdadm: /dev/sda1 has wrong uuid.
mdadm: No super block found on /dev/sda (Expected magic a92b4efc, got a0ddb71c)
mdadm: no RAID superblock on /dev/sda
mdadm: cannot open device /dev/sr0: No medium found
mdadm: /dev/sdd2 is identified as a member of /dev/md/2, slot 1.
mdadm: /dev/sdc2 is identified as a member of /dev/md/2, slot 0.
mdadm: failed to add /dev/sdd2 to /dev/md/2: Invalid argument
mdadm: failed to add /dev/sdc2 to /dev/md/2: Invalid argument
mdadm: failed to RUN_ARRAY /dev/md/2: Invalid argument

~$ sudo mdadm --assemble /dev/md2 --uuid=4b13781e:ea3a8209:74173443:77c65a9d --verbose
mdadm: looking for devices for /dev/md2
mdadm: no recogniseable superblock on /dev/md/0
mdadm: no recogniseable superblock on /dev/md/1
mdadm: No super block found on /dev/sdd1 (Expected magic a92b4efc, got 00000000)
mdadm: no RAID superblock on /dev/sdd1
mdadm: No super block found on /dev/sdd (Expected magic a92b4efc, got 00000000)
mdadm: no RAID superblock on /dev/sdd
mdadm: No super block found on /dev/sdc1 (Expected magic a92b4efc, got 00000000)
mdadm: no RAID superblock on /dev/sdc1
mdadm: No super block found on /dev/sdc (Expected magic a92b4efc, got 00000000)
mdadm: no RAID superblock on /dev/sdc
mdadm: No super block found on /dev/sdb4 (Expected magic a92b4efc, got 00000000)
mdadm: no RAID superblock on /dev/sdb4
mdadm: No super block found on /dev/sdb3 (Expected magic a92b4efc, got 00000000)
mdadm: no RAID superblock on /dev/sdb3
mdadm: /dev/sdb2 has wrong uuid.
mdadm: /dev/sdb1 has wrong uuid.
mdadm: No super block found on /dev/sdb (Expected magic a92b4efc, got a0ddb71c)
mdadm: no RAID superblock on /dev/sdb
mdadm: No super block found on /dev/sda4 (Expected magic a92b4efc, got 00000000)
mdadm: no RAID superblock on /dev/sda4
mdadm: No super block found on /dev/sda3 (Expected magic a92b4efc, got 00000000)
mdadm: no RAID superblock on /dev/sda3
mdadm: /dev/sda2 has wrong uuid.
mdadm: /dev/sda1 has wrong uuid.
mdadm: No super block found on /dev/sda (Expected magic a92b4efc, got a0ddb71c)
mdadm: no RAID superblock on /dev/sda
mdadm: cannot open device /dev/sr0: No medium found
mdadm: /dev/sdd2 is identified as a member of /dev/md2, slot 1.
mdadm: /dev/sdc2 is identified as a member of /dev/md2, slot 0.
mdadm: failed to add /dev/sdd2 to /dev/md2: Invalid argument
mdadm: failed to add /dev/sdc2 to /dev/md2: Invalid argument
mdadm: failed to RUN_ARRAY /dev/md2: Invalid argument

~$ cat /proc/mdstat 
Personalities : [raid1] [linear] [multipath] [raid0] [raid6] [raid5] [raid4] [raid10] 
md0 : active raid1 sda1[0] sdb1[1]
      1949696 blocks super 1.2 [2/2] [UU]

md1 : active raid1 sdb2[1] sda2[0]
      97589248 blocks super 1.2 [2/2] [UU]

unused devices: <none>

~$ sudo modprobe raid1
~$ sudo mdadm --assemble /dev/md2 --uuid=4b13781e:ea3a8209:74173443:77c65a9d --verbose --force --update=summaries
mdadm: looking for devices for /dev/md2
mdadm: no recogniseable superblock on /dev/md/0
mdadm: no recogniseable superblock on /dev/md/1
mdadm: No super block found on /dev/sdd1 (Expected magic a92b4efc, got 00000000)
mdadm: no RAID superblock on /dev/sdd1
mdadm: No super block found on /dev/sdd (Expected magic a92b4efc, got 00000000)
mdadm: no RAID superblock on /dev/sdd
mdadm: No super block found on /dev/sdc1 (Expected magic a92b4efc, got 00000000)
mdadm: no RAID superblock on /dev/sdc1
mdadm: No super block found on /dev/sdc (Expected magic a92b4efc, got 00000000)
mdadm: no RAID superblock on /dev/sdc
mdadm: No super block found on /dev/sdb4 (Expected magic a92b4efc, got 00000000)
mdadm: no RAID superblock on /dev/sdb4
mdadm: No super block found on /dev/sdb3 (Expected magic a92b4efc, got 00000000)
mdadm: no RAID superblock on /dev/sdb3
mdadm: /dev/sdb2 has wrong uuid.
mdadm: /dev/sdb1 has wrong uuid.
mdadm: No super block found on /dev/sdb (Expected magic a92b4efc, got a0ddb71c)
mdadm: no RAID superblock on /dev/sdb
mdadm: No super block found on /dev/sda4 (Expected magic a92b4efc, got 00000000)
mdadm: no RAID superblock on /dev/sda4
mdadm: No super block found on /dev/sda3 (Expected magic a92b4efc, got 00000000)
mdadm: no RAID superblock on /dev/sda3
mdadm: /dev/sda2 has wrong uuid.
mdadm: /dev/sda1 has wrong uuid.
mdadm: No super block found on /dev/sda (Expected magic a92b4efc, got a0ddb71c)
mdadm: no RAID superblock on /dev/sda
mdadm: cannot open device /dev/sr0: No medium found
mdadm: --update=summaries not understood for 1.x metadata
double free or corruption (!prev)
Avbruten (SIGABRT)

~$ dmesg    
[lör aug 18 08:35:54 2018] md: md2 stopped.
[lör aug 18 08:35:54 2018] md: sdd2 does not have a valid v1.2 superblock, not importing!
[lör aug 18 08:35:54 2018] md: md_import_device returned -22
[lör aug 18 08:35:54 2018] md: md2 stopped.