Configure RAID 1

Configure RAID 1 2015/10/23

	Configure RAID 1 to add 2 new HDDs on a server.
[1]	This example is based on the environment below. The new HDD sdb and sdc are newly added on it and configure RAID 1.

[root@dlp ~]#  df -h  Filesystem Size Used Avail Use% Mounted on /dev/mapper/centos-root 196G 1.2G 195G 1% / devtmpfs 1.9G 0 1.9G 0% /dev tmpfs 1.9G 0 1.9G 0% /dev/shm tmpfs 1.9G 8.5M 1.9G 1% /run tmpfs 1.9G 0 1.9G 0% /sys/fs/cgroup /dev/sda1 497M 222M 276M 45% /boot

[2]	Create a partition on new HDD and set RAID flag.

[root@dlp ~]#  parted --script /dev/sdb "mklabel gpt"  [root@dlp ~]#  parted --script /dev/sdc "mklabel gpt"  [root@dlp ~]#  parted --script /dev/sdb "mkpart primary 0% 100%"  [root@dlp ~]#  parted --script /dev/sdc "mkpart primary 0% 100%"  [root@dlp ~]#  parted --script /dev/sdb "set 1 raid on"  [root@dlp ~]#  parted --script /dev/sdc "set 1 raid on"

[3]	Configure RAID 1.

[root@dlp ~]#  yum -y install mdadm [root@dlp ~]#  mdadm --create /dev/md0 --level=raid1 --raid-devices=2 /dev/sdb1 /dev/sdc1  mdadm: Note: this array has metadata at the start and may not be suitable as a boot device. If you plan to store '/boot' on this device please ensure that your boot-loader understands md/v1.x metadata, or use --metadata=0.90 Continue creating array? y mdadm: Defaulting to version 1.2 metadata mdadm: array /dev/md0 started. # show status [root@dlp ~]#  cat /proc/mdstat  Personalities : [raid1] md0 : active raid1 sdc1[1] sdb1[0] 83818496 blocks super 1.2 [2/2] [UU] [======>..............] resync = 31.0% (26044416/83818496) finish=4.7min speed=201190K/sec unused devices: <none> # after few hours later, status turns like follows if syncing finished [root@dlp ~]#  cat /proc/mdstat  Personalities : [raid1] md0 : active raid1 sdc1[1] sdb1[0] 83818496 blocks super 1.2 [2/2] [UU] unused devices: <none> [root@dlp ~]#  vi /etc/sysconfig/raid-check # line 57: add RAID devices which you'd like to check by Cron CHECK_DEVS=" md0 "

[4]	For example, if a member HDD in RAID array would be failure, re-configure RAID 1 like follows.

# the status is like follows in failure [root@dlp ~]#  cat /proc/mdstat  Personalities : [raid1] md0 : active (auto-read-only) raid1 sdb1[0] 83818496 blocks super 1.2 [2/1] [U_] unused devices: <none> # after swapping new disk, re-configure like follows [root@dlp ~]#  mdadm --manage /dev/md0 --add /dev/sdc1  mdadm: added /dev/sdc1 [root@dlp ~]#  cat /proc/mdstat  Personalities : [raid1] md0 : active raid1 sdc1[1] sdb1[0] 83818496 blocks super 1.2 [2/2] [UU] [======>..............] resync = 31.0% (26044416/83818496) finish=4.7min speed=201190K/sec unused devices: <none>