I have raid 1, status degraded, on a D-link DNS323 running the alt-F firmware.

I have run the commands below and think I now need to run:

mdadm --add /dev/md0 /dev/sda2

Any advice will be most welcome.

sfdisk -l -uS

Disk /dev/sda: 97451 cylinders, 255 heads, 63 sectors/track
Warning: The partition table looks like it was made
for C/H/S=*/256/63 (instead of 97451/255/63).
For this listing I'll assume that geometry.
Units = sectors of 512 bytes, counting from 0

Device Boot Start End #sectors Id System
/dev/sda1 1 - 4294967295 ee Intel EFI GUID Partition Table
/dev/sda2 0 - 0 0 Empty
/dev/sda3 0 - 0 0 Empty
/dev/sda4 0 - 0 0 Empty

Disk /dev/sdb: 97451 cylinders, 255 heads, 63 sectors/track
Warning: The partition table looks like it was made
for C/H/S=*/256/63 (instead of 97451/255/63).
For this listing I'll assume that geometry.
Units = sectors of 512 bytes, counting from 0

Device Boot Start End #sectors Id System
/dev/sdb1 1 - 4294967295 ee Intel EFI GUID Partition Table
/dev/sdb2 0 - 0 0 Empty
/dev/sdb3 0 - 0 0 Empty
/dev/sdb4 0 - 0 0 Empty

more /etc/mdadm.conf

ARRAY /dev/md/0 metadata=1.2 UUID=59691fcb:f60641ea:8008509f:b752ed83 name=dlink-and:0
DEVICES /dev/sd*

cat /proc/mdstat

Personalities : [linear] [raid1]
md0 : active raid1 sdb2[2]
2929741087 blocks super 1.2 [2/1] [_U]
bitmap: 8/22 pages [32KB], 65536KB chunk

unused devices:

mdadm --detail /dev/md0

/dev/md0:
Version : 1.2
Creation Time : Sat Mar 16 23:54:30 2013
Raid Level : raid1
Array Size : 2929741087 (2794.02 GiB 3000.05 GB)
Used Dev Size : 2929741087 (2794.02 GiB 3000.05 GB)
Raid Devices : 2
Total Devices : 1
Persistence : Superblock is persistent

Intent Bitmap : Internal

Update Time : Wed Jan 12 01:14:11 2022
      State : active, degraded

Active Devices : 1
Working Devices : 1
Failed Devices : 0
Spare Devices : 0

       Name : dlink-and:0  (local to host dlink-and)
       UUID : 59691fcb:f60641ea:8008509f:b752ed83
     Events : 28427

Number   Major   Minor   RaidDevice State
   0       0        0        0      removed
   2       8       18        1      active sync   /dev/sdb2