RAID AND YOU

Been going over software RAID in CentOS 6.5 for my LFCS exam that is next week. Here are my notes so that I don't forget.

• mdadm
• This is the tool you want to use to create software RAID
• /etc/mdadm.conf (Main configuration file)
• Syntax
• mdadm -C -v <device name> --level=<raid level> --raid-devices=<#> <dev files>
• EX: mdadm -C -v /dev/rd0 --level=raid0 --raid-devices=2 /dev/sdb /dev/sdc
• This will create a raid array named /dev/rd0 out of two arbitrary HDs
• You will need to format those two drives the same way you normally would with mkfs and whatnot.
• EX: mdadm --stop /dev/md0        #Stops the Array
• EX: mdadm --remove /dev/md0  #Disassembles the array
• You can use mdadm to do some other cool things. Here are a couple:
• Set up monitoring services
• Run the following command to append the appropriate info to the /etc/mdadm.conf
• mdadm --detail --scan >> /etc/mdadm.conf
• This will tell the mdadm service to monitor any raid arrays.
• The "mdadm --detail --scan" command will give details about the drive.
• Verify that the mdadm monitor service is running and that it is set to start at boot
• sysvinit - #service mdmonitor start
• sysvinit - #chkconfig mdmonitor on
• systemd - #systemctl start mdmonitor
• systemd - #systemctl enable mdmonitor
• Setup mail alerts
• echo "MAILADDR root" >> /etc/mdadm.conf
• This will append the local root host as the address
• Check array details
• cat /proc/mdstat (less detailed summary)
• mdadm --detail /dev/md0 (more detailed summary

So there's my rundown - As always, this is all valid for CentOS - I can't attest to other distros. It's quick. It's dirty. Most of all, it's efficient. I like it.