RAID | MDADM

• Creating RAID and mounting it
• Extending RAID
• Troubleshooting RAID

Creating RAID and mounting it

Is [[Formatting - Drives]] needed? Do that first, then come back.

See if mdadm is installed or not
mdadm

  If not, install it
  apt install mdadm

Check for all storage drives in system
lsblk

Create the RAID with the drive you are going to use
mdadm --create /dev/md111((create your own file name)) --level=5 --raid-devices=4 /dev/sda1 /dev/sdb1 /dev/sdc1 /dev/sdd1

Check to see if the array is in progress
cat /proc/mdstat

Check the block ID for the new virtual drive/s
blkid

Make a File System on that new drive
mkfs.ext4 /dev/md111 (find your own disk location)

mkfs.ext4 - .ext4 means the "type" of file. shown on "sudo blkin" then state locate of the file its going to be

Create a location to mount the new virtual drive/s
"/" is a good place to start

Mount the RAID to the storage location
mount /dev/md111 /sirstorage

Check to see if the RAID is in the location you created
df -h
sudo mdadm --detail /dev/md111 <----Local RAID location

Add array to the fstab file | this will mount the array every time the computer starts up. You can do this with as many mounts/drives as you like. 
nano /etc/fstab
           look at the headers and include this under the correct header
        File system: `/dev/md111` mount point: `/storage/location` type: `ext4` options: `errors=remount-ro` put zeros on the rest.

Test to see if array mount worked
umount /storage/location
mount -a

**Reboot!!**
    Reboot the system, just in case. Make sure the array is still mounting after reboot. If its there, you are good to go son!

Need to extend your RAID? Go find that one. "Extending RAID"

Extending RAID

Prepare new disk
                Need to partition? Do it now. I'll wait...

Setup: The current RAID has 4 drives and we want to add a 5th drive. The current array is "md111" and we have already checked drives on the system lsblk to see which drive we will be adding "sdd1"

Add disk to RAID
mdadm --add /dev/md111 /dev/sdd1

mdadm --add /current/drive/array (array that already has the other raid dirves in it) /new/drive/to/add (the 1 drive that you will be adding)

Grow RAID:
mdadm --grow --raid-devices=4 /dev/md111 This will grow your current array to accept a new drive

Now that you have expanded the underlying partition, you must now resize your filesystem to take advantage of it.
You may want to perform an fsck on the file system first to make sure there are no underlying issues before attempting to resize the file system

Integrity Check: e2fsck -f /dev/md111

Resize array: resize2fs /dev/md111

Mount it: mount /dev/md111 /your/new/local/location

Check RAID rebuild status or Current status
cat /proc/mdstat

Sources you can use:
https://raid.wiki.kernel.org/index.php/Growing

Troubleshooting RAID

Setup: Our current RAID array with 5 drives in it is "md111". Its location is /dev/md111

Resize the blocks
resize2fs -f /dev/md111

Stop Array
mdadm --stop /dev/md111

Auto scan for arrays
mdadm --assemble --scan

Once the new mdadm.conf was ready, execute "sudo update-initramfs -u" This updats the conf file used by initramfs.
sudo update-initramfs -u