First of all, I am an absolute beginner with Ubuntu Server. I decided to build my own server and running it with 4x 3TB drives in a software RAID mounted as /home and an SSD with the OS on it.
When I first created the Raid it reported the correct size, but after a reboot /dev/md0 went missing. So I rebuilt again.
But this time, the size of /dev/md0 is 1 disk less than previously
lsblk outputs:
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
sda 8:0 0 2.7T 0 disk
└─sda1 8:1 0 2.7T 0 part
└─md0 9:0 0 5.5T 0 raid5 /home
sdb 8:16 0 2.7T 0 disk
└─sdb1 8:17 0 2.7T 0 part
└─md0 9:0 0 5.5T 0 raid5 /home
sdc 8:32 0 2.7T 0 disk
└─sdc1 8:33 0 2.7T 0 part
└─md0 9:0 0 5.5T 0 raid5 /home
sdd 8:48 0 2.7T 0 disk
└─sdd1 8:49 0 2.7T 0 part
└─md0 9:0 0 5.5T 0 raid5 /home
sde 8:64 0 55.9G 0 disk
├─sde1 8:65 0 512M 0 part /boot/efi
├─sde2 8:66 0 39.5G 0 part /
└─sde3 8:67 0 15.9G 0 part [SWAP]
sd[abcd]1 are obviously 2.7T, how come mdadm created the array with one drive missing?
cat /proc/mdstat
Personalities : [linear] [multipath] [raid0] [raid1] [raid6] [raid5] [raid4] [raid10]
md0 : active raid5 sdb1[1] sda1[4](S) sdd1[3] sdc1[2]
5860267008 blocks super 1.2 level 5, 512k chunk, algorithm 2 [3/3] [UUU]
Any advice is appreciated