RAID

Features:
1. The ability to increase availability and reliability of data


Tasks:
1. Create a RAID-1 Device (/dev/md0..n)
a. fdisk /dev/sdb - to create usable raw partitions
b. partprobe /dev/sdb - to force a kernel update of the partition layout of the disk: /dev/sdb
b. mdadm --create /dev/md0 --level=1 --raid-devices=2 /dev/sdb5 /dev/sdb6
c. cat /proc/mdstat - lists active RAID (md) information
d. mke2fs -j /dev/md0 - overlays a file system on the RAID device
e. mount /dev/md0 /raid1
f. update: /etc/fstab

Note: use 'mdadm --query /dev/md0' to get information about a RAID device


Note: You may create RAID volumes/devices on a single or on multiple disks
Ideally, your RAID volumes should span multiple physical disks to improve:
a. reliability
b. performance
c. availability

2. Remove the RAID-1 device
a. umount /dev/md0
b. mdadm --manage --stop /dev/md0

3. Create a RAID-5 Volume
a. fdisk /dev/sdb - to create a partition number 7
b. partprobe /dev/sdb - to update the kernel's view of the partition table
c. mdadm --create /dev/md0 --level=5 --raid-devices=3 /dev/sdb5 /dev/sdb6 /dev/sdb7
d. watch cat /proc/mdstat - refreshes every 2 seconds
e. Overlay a file system: mke2fs -j /dev/md0
f. mount /dev/md0 /raid5
g. Test I/O to RAID-5 device
h. Update: /etc/fstab