mdadm Linux Software RAID QuickStart Guide

Create New RAID 1 Array:

First setup your partitions (make sure they are exactly the same size)
In my example I have sda3 and sdb3 which are 500GB in size.

mdadm --create /dev/md2 --level=1 --raid-devices=2 /dev/sda3 /dev/sdb3
mdadm: array /dev/md2 started.

Check Status Of The Array

*Note I already have other arrays md0 and md1.

You can see below that md2 is syncing at a speed of about 91MB per sec.

cat /proc/mdstat


Personalities : [raid1]
md2 : active raid1 sdb3[1] sda3[0]
488287552 blocks [2/2] [UU]
[>....................] resync = 0.5% (2460992/488287552) finish=88.8min speed=91147K/sec

md1 : active raid1 sda2[0] sdb2[1]
29302464 blocks [2/2] [UU]

md0 : active raid1 sdb1[1] sda1[0]
58604992 blocks [2/2] [UU]

unused devices:

Check the basic details of an array:



mdadm /dev/md0
/dev/md0: 55.89GiB raid1 2 devices, 0 spares. Use mdadm --detail for more detail.
/dev/md0: No md super block found, not an md component.


More Detail

mdadm --detail /dev/md0

/dev/md0:
Version : 0.90
Creation Time : Tue Aug 31 22:37:52 2010
Raid Level : raid1
Array Size : 58604992 (55.89 GiB 60.01 GB)
Used Dev Size : 58604992 (55.89 GiB 60.01 GB)
Raid Devices : 2
Total Devices : 2
Preferred Minor : 0
Persistence : Superblock is persistent

Update Time : Wed Sep 1 18:39:53 2010
State : active
Active Devices : 2
Working Devices : 2
Failed Devices : 0
Spare Devices : 0

UUID : 7b4e9a42:823c7ee5:0d6ee1b8:30df68a8
Events : 0.7

Number Major Minor RaidDevice State
0 8 1 0 active sync /dev/sda1
1 8 17 1 active sync /dev/sdb1

Update /etc/mdadm.conf File



mdadm --brief --detail /dev/md0

ARRAY /dev/md0 level=raid1 num-devices=2 metadata=0.90 UUID=7b4e9a42:823c7ee5:0d6ee1b8:30df68a8

To edit the /etc/mdadm.conf file directly just run the command like this make sure to use the ">>" or you will wipe out any existing array info.

mdadm --brief --detail /dev/md0 >> /etc/mdadm.conf


Tags:

mdadm, linux, software, raid, quickstart, array, partitions, sda, sdb, gb, dev, md, devices, arrays, syncing, mb, proc, mdstat, personalities, active, uu, resync, min, unused, gib, spares, component, creation, tue, aug, preferred, persistence, superblock, persistent, update, wed, sep, uuid, ee, df, raiddevice, sync, etc, conf, num, metadata, edit, quot, existing, info,

Latest Articles

  • Linux Ubuntu Cannot Print Large Images
  • Cannot Print PDF Solution and Howto Resize
  • Linux Console Login Screen TTY Change Message
  • Apache Cannot Start Listening Already on 0.0.0.0
  • MySQL Bash Query to pipe input directly without using heredoc trick
  • CentOS 6 and 7 / RHEL Persistent DHCP Solution
  • Debian Ubuntu Mint rc-local service startup error solution rc-local.service: Failed at step EXEC spawning /etc/rc.local: Exec format error
  • MySQL Cheatsheet Guide and Tutorial
  • bash script kill whois or other command that is running for too long
  • Linux tftp listens on all interfaces and IPs by DEFAULT Security Risk Hole Solution
  • python import docx error
  • Cisco Unified Communications Manager Express Cheatsheet CUCME CME
  • Linux Ubuntu Debian Missing privilege separation directory: /var/run/sshd
  • bash how to count the number of columns or words in a line
  • bash if statement how to test program output without assigning to variable
  • RTNETLINK answers: Network is unreachable
  • Centos 7 how to save iptables rules like Centos 6
  • nfs tuning maximum amount of connections
  • qemu-kvm error "Could not initialize SDL(No available video device) - exiting"
  • Centos 7 tftpd will not work with selinux enabled