Convert to RAID: Difference between revisions
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Latest revision as of 15:39, 22 July 2009
Partition new disk
[root@centos ~]# fdisk -l /dev/hda Disk /dev/hda: 20.0 GB, 20020396032 bytes 255 heads, 63 sectors/track, 2434 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Device Boot Start End Blocks Id System /dev/hda1 * 1 13 104391 83 Linux /dev/hda2 14 2434 19446682+ 8e Linux LVM [root@centos ~]# fdisk -l /dev/hdb Disk /dev/hdb: 40.0 GB, 40000000000 bytes 255 heads, 63 sectors/track, 4863 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Device Boot Start End Blocks Id System [root@centos ~]# cat /etc/fstab /dev/vg0/root / ext3 noatime 1 1 /dev/vg0/tmp /tmp ext2 noatime 1 2 /dev/vg0/home /home ext3 noatime 1 2 /dev/vg0/var /var ext3 noatime 1 2 /dev/vg0/usr /usr ext3 noatime 1 2 LABEL=/boot /boot ext2 noatime 1 2 tmpfs /dev/shm tmpfs defaults 0 0 devpts /dev/pts devpts gid=5,mode=620 0 0 sysfs /sys sysfs defaults 0 0 proc /proc proc defaults 0 0 /dev/vg0/swap swap swap defaults 0 0 [root@centos ~]# fdisk /dev/hdb The number of cylinders for this disk is set to 4863. There is nothing wrong with that, but this is larger than 1024, and could in certain setups cause problems with: 1) software that runs at boot time (e.g., old versions of LILO) 2) booting and partitioning software from other OSs (e.g., DOS FDISK, OS/2 FDISK) Command (m for help): n Command action e extended p primary partition (1-4) p Partition number (1-4): 1 First cylinder (1-4863, default 1): Using default value 1 Last cylinder or +size or +sizeM or +sizeK (1-4863, default 4863): 13 Command (m for help): t Selected partition 1 Hex code (type L to list codes): FD Changed system type of partition 1 to fd (Linux raid autodetect) Command (m for help): n Command action e extended p primary partition (1-4) p Partition number (1-4): 2 First cylinder (14-4863, default 14): Using default value 14 Last cylinder or +size or +sizeM or +sizeK (14-4863, default 4863): +512M Command (m for help): t Partition number (1-4): 2 Hex code (type L to list codes): 82 Changed system type of partition 2 to 82 (Linux swap / Solaris) Command (m for help): n Command action e extended p primary partition (1-4) p Partition number (1-4): 3 First cylinder (77-4863, default 77): Using default value 77 Last cylinder or +size or +sizeM or +sizeK (77-4863, default 4863): 2434 Command (m for help): t Partition number (1-4): 3 Hex code (type L to list codes): FD Changed system type of partition 3 to fd (Linux raid autodetect) Command (m for help): p Disk /dev/hdb: 40.0 GB, 40000000000 bytes 255 heads, 63 sectors/track, 4863 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Device Boot Start End Blocks Id System /dev/hdb1 1 13 104391 fd Linux raid autodetect /dev/hdb2 14 76 506047+ 82 Linux swap / Solaris /dev/hdb3 77 2434 18940635 fd Linux raid autodetect Command (m for help): w The partition table has been altered! Calling ioctl() to re-read partition table. Syncing disks.
The new disk was larger, partition sizes were calculated based on old disk size.
Switch to new swap partition
- Note: You have to make a decision what is more important to you. If you want your system to continue to run in case of a hard disk failure, you need to go with 'swap on raid ' approach: don't create separate swap partitions, but instead create a swap logical volume in the new volume group. If performance is more important, then you split your swap between two disks and create separate swap partitions on each disk, as I did in this document.
[root@centos ~]# mkswap -L swapb /dev/hdb2 Setting up swapspace version 1, size = 518184 kB LABEL=swapb, no uuid [root@centos ~]# swapon /dev/hdb2 [root@centos ~]# swapoff /dev/vg0/swap
Install required packages
yum -y install mdadm dump
Create degraded RAID arrays
[root@centos ~]# mdadm --create /dev/md0 --level=1 --raid-devices=2 /dev/hdb1 missing mdadm: array /dev/md0 started. [root@centos ~]# mdadm --create /dev/md1 --level=1 --raid-devices=2 /dev/hdb3 missing mdadm: array /dev/md1 started. [root@centos ~]# mdadm --examine --scan > /etc/mdadm.conf
Create new volume group
[root@centos ~]# pvcreate /dev/md1 Physical volume "/dev/md1" successfully created [root@centos ~]# vgcreate -s 32M vg1 /dev/md1 Volume group "vg1" successfully created [root@centos ~]# lvcreate --size 512M --name root vg1 Logical volume "root" created [root@centos ~]# lvcreate --size 4G --name usr vg1 Logical volume "usr" created [root@centos ~]# lvcreate --size 1G --name var vg1 Logical volume "var" created [root@centos ~]# lvcreate --size 1G --name home vg1 Logical volume "home" created [root@centos ~]# lvcreate --size 256M --name tmp vg1 Logical volume "tmp" created
Format new filesystems
mkfs -j /dev/vg1/root mkfs -j /dev/vg1/usr mkfs -j /dev/vg1/var mkfs -j /dev/vg1/home mkfs /dev/vg1/tmp mkfs /dev/md0
Shutdown all services
Keep sshd running, stop the rest
service crond stop service syslog stop ...
Mount/transfer root volume
mount -t ext3 /dev/vg1/root /mnt/ cd /mnt/ dump -0 -f - /dev/vg0/root | restore -r -f - rm restoresymtable
Mount/transfer remaining volumes
mount -t ext3 /dev/vg1/usr /mnt/usr/ mount -t ext3 /dev/vg1/var /mnt/var/ mount -t ext3 /dev/vg1/home /mnt/home/ mount -t ext2 /dev/vg1/tmp /mnt/tmp/ chmod 1777 /mnt/tmp mount -t ext2 /dev/md0 /mnt/boot/ cd /mnt/usr dump -0 -f - /dev/vg0/usr | restore -r -f - rm restoresymtable cd /mnt/var dump -0 -f - /dev/vg0/var | restore -r -f - rm restoresymtable cd /mnt/home dump -0 -f - /dev/vg0/home | restore -r -f - rm restoresymtable cd /mnt/boot dump -0 -f - /dev/hda1 | restore -r -f - rm restoresymtable
No need to dump/restore /tmp
chroot to new system
mkdir /mnt/dev/pts mount -t devpts devpts /mnt/dev/pts mount -t sysfs sysfs /mnt/sys mount -t proc proc /mnt/proc mkdir /mnt/dev/shm mount -t tmpfs tmpfs /mnt/dev/shm chroot /mnt start_udev
adjust /etc/fstab
[root@centos /]# cat /etc/fstab /dev/vg1/root / ext3 noatime 1 1 /dev/vg1/tmp /tmp ext2 noatime 1 2 /dev/vg1/home /home ext3 noatime 1 2 /dev/vg1/var /var ext3 noatime 1 2 /dev/vg1/usr /usr ext3 noatime 1 2 /dev/md0 /boot ext2 noatime 1 2 tmpfs /dev/shm tmpfs defaults 0 0 devpts /dev/pts devpts gid=5,mode=620 0 0 sysfs /sys sysfs defaults 0 0 proc /proc proc defaults 0 0 LABEL=swapb swap swap pri=1 0 0
adjust /etc/grub.conf
default=1 timeout=5 #splashimage=(hd0,0)/grub/splash.xpm.gz hiddenmenu title CentOS (2.6.18-128.2.1.el5) root (hd0,0) kernel /vmlinuz-2.6.18-128.2.1.el5 ro root=/dev/vg0/root initrd /initrd-2.6.18-128.2.1.el5.img title CentOS (2.6.18-128.2.1.el5) root (hd1,0) kernel /vmlinuz-2.6.18-128.2.1.el5 ro root=/dev/vg1/root initrd /initrd-2.6.18-128.2.1.el5.img
adjust /etc/mdadm.conf
DEVICE partitions MAILADDR root ARRAY /dev/md0 level=raid1 num-devices=2 UUID=8ca072a8:085c91c0:52eada7c:6cc0931c ARRAY /dev/md1 level=raid1 num-devices=2 UUID=898f5b3c:670dcb6c:d422cdf5:eddafb24
recreate initrd image
cd /boot mkinitrd -f initrd-2.6.18-128.2.1.el5.img -v 2.6.18-128.2.1.el5
copy new grub.conf to old disk
exit # from chroot cp /mnt/etc/grub.conf /etc/grub.conf
Update bootloader configuration
grub-install --recheck /dev/hda
reboot to new system on the raid
reboot
verify new installation
Make sure system is operational and everything is in order. Up to this step all changes made were non-destructive and you could boot your old system from the grub menu.
Delete old volume group
This step is not really necessary, you could have reformatted the first disk, but this OS-friendly approach.
lvremove /dev/vg0/root lvremove /dev/vg0/usr lvremove /dev/vg0/var lvremove /dev/vg0/tmp lvremove /dev/vg0/swap vgremove vg0 pvremove /dev/hda2
delete and create new partitions on the old disk
You the same commands as before
[root@centos ~]# fdisk -l /dev/hda Disk /dev/hda: 20.0 GB, 20020396032 bytes 255 heads, 63 sectors/track, 2434 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Device Boot Start End Blocks Id System /dev/hda1 1 13 104391 fd Linux raid autodetect /dev/hda2 14 76 506047+ 82 Linux swap / Solaris /dev/hda3 77 2434 18940635 fd Linux raid autodetect
Add additional swap
mkswap -L swapa /dev/hda2
Add entry to /etc/fstab
LABEL=swapa swap swap pri=1 0 0
Add partitions to raid
mdadm --add /dev/md0 /dev/hda1 mdadm --add /dev/md1 /dev/hda3
wait until RAID fully synchronized:
# watch cat /proc/mdstat
Every 2.0s: cat /proc/mdstat Wed Jul 22 18:21:38 2009
Personalities : [raid1]
md0 : active raid1 hda1[1] hdb1[0]
104320 blocks [2/2] [UU]
md1 : active raid1 hda3[2] hdb3[0]
18940544 blocks [2/1] [U_]
[=>...................] recovery = 7.3% (1398400/18940544) finish=11.3min speed=25826K/sec
unused devices: <none>
Adjust grub.conf
default=0 timeout=5 hiddenmenu title CentOS (2.6.18-128.2.1.el5) root (hd0,0) kernel /vmlinuz-2.6.18-128.2.1.el5 ro root=/dev/vg1/root initrd /initrd-2.6.18-128.2.1.el5.img
Install bootloader on second disk
# grub grub> device (hd0) /dev/hdb grub> root (hd0,0) grub> setup (hd0) grub> quit
Final reboot
shutdown -r now
Enjoy
