I created a raid1 using the below disks and command:
$ ls -l /dev/disk/by-id/ata-ST3000*
lrwxrwxrwx 1 root root 9 Sep 19 07:27 /dev/disk/by-id/ata-ST3000DM001-9YN166_Z1F04NR1 -> ../../sdc
lrwxrwxrwx 1 root root 9 Sep 19 07:27 /dev/disk/by-id/ata-ST3000DM001-9YN166_Z1F190E3 -> ../../sda
$ mdadm --create /dev/md0 --level=1 --raid-devices=2 /dev/disk/by-id/ata-ST3000DM001-9YN166_Z1F190E3 /dev/disk/by-id/ata-ST3000DM001-9YN166_Z1F04NR1
I added the pertinent information to mdadm.conf. I used 'mdadm --detail --scan >> /etc/mdadm.conf' for the ARRAY line:
$ cat /etc/mdadm.conf
DEVICE /dev/disk/by-id/ata-ST3000DM001-9YN166_Z1F190E3
DEVICE /dev/disk/by-id/ata-ST3000DM001-9YN166_Z1F04NR1
ARRAY /dev/md0 metadata=1.2 name=jaime.WORKGROUP:0 UUID=93f2cb73:2d124630:562f1dd9:bf189029
MAILADDR your@address
I created and mounted the filesystem:
$ mkfs -t xfs /dev/md0
$ mount -t xfs /dev/md0 /data
After rebooting, /dev/md0 no longer exists and I can't assemble the array:
$ mdadm --assemble /dev/md0 /dev/disk/by-id/ata-ST3000DM001-9YN166_Z1F190E3 /dev/disk/by-id/ata-ST3000DM001-9YN166_Z1F04NR1
mdadm: Cannot assemble mbr metadata on /dev/disk/by-id/ata-ST3000DM001-9YN166_Z1F190E3
mdadm: /dev/disk/by-id/ata-ST3000DM001-9YN166_Z1F190E3 has no superblock - assembly aborted
$ blkid
/dev/sda: PTTYPE="gpt"
/dev/sdb1: UUID="5c7d3f2b-c975-46a3-a116-e9fc156c1de5" TYPE="xfs"
/dev/sdb2: UUID="JhoqjI-N6R6-O9zt-Xumq-TnFX-OUCd-Lg9YHy" TYPE="LVM2_member"
/dev/sdc: PTTYPE="gpt"
/dev/mapper/centos-swap: UUID="3b882d4d-b900-4c59-9912-60a413699db4" TYPE="swap"
/dev/mapper/centos-root: UUID="08df953d-d4f4-4e83-bf4b-41f14a98a12e" TYPE="xfs"
/dev/mapper/centos-home: UUID="2358f723-5e7f-49ed-b207-f32fe34b1bbc" TYPE="xfs"
blkid
orlsblk
. Also look in the output ofdmesg
for any messages related to the RAID./dev/disk/by-id/...
used when constructing RAIDs. You typically use/dev/sda1
/dev/sdb1
, where these are partitions on the device that were created usingparted
,fdisk
, orgdisk
.