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Configure RAID 1
2011/05/10 |
| Configure RAID 1. This example set /home for it. It needs at least 2 disks that have enough free area, if your computer does not have such disks, add disks in your computer, or configure iSCSI to attach network storage. |
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| [1] | Create a RAID partition on each disks. See here to create a partiton. The example in the link creates LVM partiton, but be careful, create a RAID partiton on here. The partition type of RAID is just "fd". Specify it for partition type. After creating RAID partition, the status of disks is just like follows. |
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[root@dlp ~]# sfdisk -l /dev/sdb Disk /dev/sdb: 20886 cylinders, 255 heads, 63 sectors/track Units = cylinders of 8225280 bytes, blocks of 1024 bytes, counting from 0 Device Boot Start End #cyls #blocks Id System /dev/sdb1 0+ 20885 20886- 167766763+ fd Linux raid autodetect /dev/sdb2 0 - 0 0 0 Empty /dev/sdb3 0 - 0 0 0 Empty /dev/sdb4 0 - 0 0 0 Empty
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| [2] | Configure RAID 1 |
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[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. [root@dlp ~]# vi /etc/mdadm.conf # mdadm.conf written out by anaconda MAILADDR root AUTO +imsm +1.x -all # add
DEVICE /dev/sd[a-z]* ARRAY /dev/md0 level=raid1 devices=/dev/sdb1,/dev/sdc1 [root@dlp ~]# cat /proc/mdstat # show status ( it's OK if it shows "[UU]" ) Personalities : [raid1] md0 : active raid1 sdc1[1] sdb1[0] 104855127 blocks super 1.2 [2/2] [UU] [==========>..........] resync = 50.1% (52600064/104855127) finish=4.2min speed=206060K/sec unused devices: <none> # after few minutes later, syncronizeing will complete and the status turns like follows [root@dlp ~]# cat /proc/mdstat Personalities : [raid1] md0 : active raid1 sdc1[1] sdb1[0] 104855127 blocks super 1.2 [2/2] [UU] unused devices: <none> |
| [3] | Configuration completes to create a file system in RAID device and mount /home on it. |
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[root@dlp ~]# pvcreate /dev/md0 Physical volume "/dev/md0" successfully created [root@dlp ~]# vgcreate vg_home /dev/md0 Volume group "vg_home" successfully created [root@dlp ~]# lvcreate -L 50G -n lv_home vg_home Logical volume "lv_home" created [root@dlp ~]# mkfs -t ext4 /dev/vg_home/lv_home [root@dlp ~]# mount /dev/vg_home/lv_home /mnt [root@dlp ~]# cp -pR /home/* /mnt/ [root@dlp ~]# umount /mnt [root@dlp ~]# mount /dev/vg_home/lv_home /home [root@dlp ~]# df -h Filesystem 1M-blocks Used Available Use% Mounted on /dev/mapper/vg_dlp-lv_root 20G 6.9G 12G 37% / tmpfs 3.9G 0 3.9G 0% /dev/shm /dev/sda1 485M 34M 426M 8% /boot /dev/mapper/vg_home-lv_home 50G 182M 47G 1% /home [root@dlp ~]# vi /etc/fstab # add RAID ARRAY /dev/mapper/vg_home-lv_home
/home ext4 defaults 1 2 |
| [4] | Start mdmonitor to monitor RAID ARRAY |
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[root@dlp ~]# /etc/rc.d/init.d/mdmonitor start Starting mdmonitor: [ OK ] [root@dlp ~]# chkconfig mdmonitor on
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| [5] | If a hard drive in RAID ARRAY would be Failure, re-configure RAID 1 like follows. |
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# the status in failure is like follows [root@dlp ~]# cat /proc/mdstat Personalities : [raid1] md0 : active (auto-read-only) raid1 sdb1[0] 104855127 blocks super 1.2 [2/1] [U_] unused devices: <none> # change to new disk and create a raidautodetect partition on it again # next, do like follows [root@dlp ~]# mdadm --manage /dev/md0 --add /dev/sdc1 # add new partition in RAID ARRAY mdadm: added /dev/sdc1 [root@dlp ~]# cat /proc/mdstat # syncronizing starts Personalities : [raid1] md0 : active raid1 sdc1[2] sdb1[0] 104855127 blocks super 1.2 [2/1] [U_] [>....................] recovery = 4.9% (5200000/104855127) finish=7.9min speed=208000K/sec unused devices: <none> # after few minutes later, syncronizeing will complete and the status turns like follows. [root@dlp ~]# cat /proc/mdstat Personalities : [raid1] md0 : active raid1 sdc1[2] sdb1[0] 104855127 blocks super 1.2 [2/2] [UU] unused devices: <none> |