How To Set Up Software RAID1 On A Running LVM System (Incl. GRUB2 Configuration) (Ubuntu 11.10)
Abstract: 0x00000000 Disk /dev/mapper/server1-swap_1 doesn't contain a valid partition table [email protected]0x00000000 Disk /dev/mapper/server1-swap_1 doesn't
Version 1.0
Author: Falko Timme
Follow me on Twitter
This guide explains how to set up software RAID1 on an already running LVM system (Ubuntu 11.10). The GRUB2 bootloader will be configured in such a way that the system will still be able to boot if one of the hard drives fails (no matter which one).
I do not issue any guarantee that this will work for you!
1 Preliminary Note
In this tutorial I'm using an Ubuntu 11.10 system with two hard drives, /dev/sda and /dev/sdb which are identical in size. /dev/sdb is currently unused, and /dev/sda has the following partitions (this is the default Ubuntu 11.10 LVM partitioning scheme - you should find something similar on your system unless you chose to manually partition during the installation of the system):
- /dev/sda1: /boot partition, ext2;
- /dev/sda2: extended, contains /dev/sda5;
- /dev/sda5: is used for LVM (volume group server1) and contains / (volume root) and swap (volume swap_1).
In the end I want to have the following situation:
- /dev/md0 (made up of /dev/sda1 and /dev/sdb1): /boot partition, ext2;
- /dev/md1 (made up of /dev/sda5 and /dev/sdb5): LVM (volume group server1), contains / (volume root) and swap (volume swap_1).
This is the current situation:
df -h
[email protected]:~# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/server1-root
4.2G 995M 3.0G 25% /
udev 238M 4.0K 238M 1% /dev
tmpfs 99M 216K 99M 1% /run
none 5.0M 0 5.0M 0% /run/lock
none 247M 0 247M 0% /run/shm
/dev/sda1 228M 24M 193M 11% /boot
[email protected]:~#
fdisk -l
[email protected]:~# fdisk -l
Disk /dev/sda: 5368 MB, 5368709120 bytes
255 heads, 63 sectors/track, 652 cylinders, total 10485760 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x0000ad1b
Device Boot Start End Blocks Id System
/dev/sda1 * 2048 499711 248832 83 Linux
/dev/sda2 501758 10483711 4990977 5 Extended
/dev/sda5 501760 10483711 4990976 8e Linux LVM
Disk /dev/sdb: 5368 MB, 5368709120 bytes
255 heads, 63 sectors/track, 652 cylinders, total 10485760 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000
Disk /dev/sdb doesn't contain a valid partition table
Disk /dev/mapper/server1-root: 4563 MB, 4563402752 bytes
255 heads, 63 sectors/track, 554 cylinders, total 8912896 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000
Disk /dev/mapper/server1-root doesn't contain a valid partition table
Disk /dev/mapper/server1-swap_1: 532 MB, 532676608 bytes
255 heads, 63 sectors/track, 64 cylinders, total 1040384 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000
Disk /dev/mapper/server1-swap_1 doesn't contain a valid partition table
[email protected]:~#
pvdisplay
[email protected]:~# pvdisplay
--- Physical volume ---
PV Name /dev/sda5
VG Name server1
PV Size 4.76 GiB / not usable 2.00 MiB
Allocatable yes
PE Size 4.00 MiB
Total PE 1218
Free PE 3
Allocated PE 1215
PV UUID dKWi5I-GMPP-wzoP-qXfi-e93A-YVmp-A7O1IK
[email protected]:~#
vgdisplay
[email protected]:~# vgdisplay
--- Volume group ---
VG Name server1
System ID
Format lvm2
Metadata Areas 1
Metadata Sequence No 3
VG Access read/write
VG Status resizable
MAX LV 0
Cur LV 2
Open LV 2
Max PV 0
Cur PV 1
Act PV 1
VG Size 4.76 GiB
PE Size 4.00 MiB
Total PE 1218
Alloc PE / Size 1215 / 4.75 GiB
Free PE / Size 3 / 12.00 MiB
VG UUID kwDyrp-sFA7-3s3i-FVWc-AGck-NX6H-yo4Pyt
[email protected]:~#
lvdisplay
[email protected]:~# lvdisplay
--- Logical volume ---
LV Name /dev/server1/root
VG Name server1
LV UUID dNn3NY-YhPm-qE8r-Dr8L-k8CG-ECLp-YjRnGf
LV Write Access read/write
LV Status available
# open 1
LV Size 4.25 GiB
Current LE 1088
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 256
Block device 252:0
--- Logical volume ---
LV Name /dev/server1/swap_1
VG Name server1
LV UUID HKIiwv-7X8Y-rzeg-aedK-5RZo-g3Km-QjxkdL
LV Write Access read/write
LV Status available
# open 2
LV Size 508.00 MiB
Current LE 127
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 256
Block device 252:1
[email protected]:~#
2 Installing mdadm
The most important tool for setting up RAID is mdadm. Let's install it like this:
apt-get install initramfs-tools mdadm
General type of mail configuration: <-- Internet Site
System mail name: <-- server1.example.com
Afterwards, we load a few kernel modules (to avoid a reboot):
modprobe linear
modprobe multipath
modprobe raid0
modprobe raid1
modprobe raid5
modprobe raid6
modprobe raid10
Now run
cat /proc/mdstat
The output should look as follows:
[email protected]:~# cat /proc/mdstat
Personalities : [linear] [multipath] [raid0] [raid1] [raid6] [raid5] [raid4] [raid10]
unused devices: <none>
[email protected]:~#
3 Preparing /dev/sdb
To create a RAID1 array on our already running system, we must prepare the /dev/sdb hard drive for RAID1, then copy the contents of our /dev/sda hard drive to it, and finally add /dev/sda to the RAID1 array.
First, we copy the partition table from /dev/sda to /dev/sdb so that both disks have exactly the same layout:
sfdisk -d /dev/sda | sfdisk --force /dev/sdb
The output should be as follows:
[email protected]:~# sfdisk -d /dev/sda | sfdisk --force /dev/sdb
Checking that no-one is using this disk right now ...
OK
Disk /dev/sdb: 652 cylinders, 255 heads, 63 sectors/track
sfdisk: ERROR: sector 0 does not have an msdos signature
/dev/sdb: unrecognized partition table type
Old situation:
No partitions found
Warning: extended partition does not start at a cylinder boundary.
DOS and Linux will interpret the contents differently.
New situation:
Units = sectors of 512 bytes, counting from 0
Device Boot Start End #sectors Id System
/dev/sdb1 * 2048 499711 497664 83 Linux
/dev/sdb2 501758 10483711 9981954 5 Extended
/dev/sdb3 0 - 0 0 Empty
/dev/sdb4 0 - 0 0 Empty
/dev/sdb5 501760 10483711 9981952 8e Linux LVM
Warning: partition 1 does not end at a cylinder boundary
Successfully wrote the new partition table
Re-reading the partition table ...
If you created or changed a DOS partition, /dev/foo7, say, then use dd(1)
to zero the first 512 bytes: dd if=/dev/zero of=/dev/foo7 bs=512 count=1
(See fdisk(8).)
[email protected]:~#
The command
fdisk -l
should now show that both HDDs have the same layout:
[email protected]:~# fdisk -l
Disk /dev/sda: 5368 MB, 5368709120 bytes
255 heads, 63 sectors/track, 652 cylinders, total 10485760 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x0000ad1b
Device Boot Start End Blocks Id System
/dev/sda1 * 2048 499711 248832 83 Linux
/dev/sda2 501758 10483711 4990977 5 Extended
/dev/sda5 501760 10483711 4990976 8e Linux LVM
Disk /dev/sdb: 5368 MB, 5368709120 bytes
255 heads, 63 sectors/track, 652 cylinders, total 10485760 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000
Device Boot Start End Blocks Id System
/dev/sdb1 * 2048 499711 248832 83 Linux
/dev/sdb2 501758 10483711 4990977 5 Extended
/dev/sdb5 501760 10483711 4990976 8e Linux LVM
Disk /dev/mapper/server1-root: 4563 MB, 4563402752 bytes
255 heads, 63 sectors/track, 554 cylinders, total 8912896 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000
Disk /dev/mapper/server1-root doesn't contain a valid partition table
Disk /dev/mapper/server1-swap_1: 532 MB, 532676608 bytes
255 heads, 63 sectors/track, 64 cylinders, total 1040384 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000
Disk /dev/mapper/server1-swap_1 doesn't contain a valid partition table
[email protected]:~#
Next we must change the partition type of our three partitions on /dev/sdb to Linux raid autodetect:
fdisk /dev/sdb
[email protected]:~# fdisk /dev/sdb
WARNING: DOS-compatible mode is deprecated. It's strongly recommended to
switch off the mode (command 'c') and change display units to
sectors (command 'u').
Command (m for help): <-- m
Command action
a toggle a bootable flag
b edit bsd disklabel
c toggle the dos compatibility flag
d delete a partition
l list known partition types
m print this menu
n add a new partition
o create a new empty DOS partition table
p print the partition table
q quit without saving changes
s create a new empty Sun disklabel
t change a partition's system id
u change display/entry units
v verify the partition table
w write table to disk and exit
x extra functionality (experts only)
Command (m for help): <-- t
Partition number (1-5): <-- 1
Hex code (type L to list codes): <-- L
0 Empty 24 NEC DOS 81 Minix / old Lin bf Solaris
1 FAT12 39 Plan 9 82 Linux swap / So c1 DRDOS/sec (FAT-
2 XENIX root 3c PartitionMagic 83 Linux c4 DRDOS/sec (FAT-
3 XENIX usr 40 Venix 80286 84 OS/2 hidden C: c6 DRDOS/sec (FAT-
4 FAT16 <32M 41 PPC PReP Boot 85 Linux extended c7 Syrinx
5 Extended 42 SFS 86 NTFS volume set da Non-FS data
6 FAT16 4d QNX4.x 87 NTFS volume set db CP/M / CTOS / .
7 HPFS/NTFS 4e QNX4.x 2nd part 88 Linux plaintext de Dell Utility
8 AIX 4f QNX4.x 3rd part 8e Linux LVM df BootIt
9 AIX bootable 50 OnTrack DM 93 Amoeba e1 DOS access
a OS/2 Boot Manag 51 OnTrack DM6 Aux 94 Amoeba BBT e3 DOS R/O
b W95 FAT32 52 CP/M 9f BSD/OS e4 SpeedStor
c W95 FAT32 (LBA) 53 OnTrack DM6 Aux a0 IBM Thinkpad hi eb BeOS fs
e W95 FAT16 (LBA) 54 OnTrackDM6 a5 FreeBSD ee GPT
f W95 Ext'd (LBA) 55 EZ-Drive a6 OpenBSD ef EFI (FAT-12/16/
10 OPUS 56 Golden Bow a7 NeXTSTEP f0 Linux/PA-RISC b
11 Hidden FAT12 5c Priam Edisk a8 Darwin UFS f1 SpeedStor
12 Compaq diagnost 61 SpeedStor a9 NetBSD f4 SpeedStor
14 Hidden FAT16 <3 63 GNU HURD or Sys ab Darwin boot f2 DOS secondary
16 Hidden FAT16 64 Novell Netware af HFS / HFS+ fb VMware VMFS
17 Hidden HPFS/NTF 65 Novell Netware b7 BSDI fs fc VMware VMKCORE
18 AST SmartSleep 70 DiskSecure Mult b8 BSDI swap fd Linux raid auto
1b Hidden W95 FAT3 75 PC/IX bb Boot Wizard hid fe LANstep
1c Hidden W95 FAT3 80 Old Minix be Solaris boot ff BBT
1e Hidden W95 FAT1
Hex code (type L to list codes): <-- fd
Changed system type of partition 1 to fd (Linux raid autodetect)
Command (m for help): <-- t
Partition number (1-5): <-- 5
Hex code (type L to list codes): <-- fd
Changed system type of partition 5 to fd (Linux raid autodetect)
Command (m for help): <-- w
The partition table has been altered!
Calling ioctl() to re-read partition table.
Syncing disks.
[email protected]:~#
The command
fdisk -l
should now show that /dev/sdb1 and /dev/sdb5 are of the type Linux raid autodetect:
[email protected]:~# fdisk -l
Disk /dev/sda: 5368 MB, 5368709120 bytes
255 heads, 63 sectors/track, 652 cylinders, total 10485760 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x0000ad1b
Device Boot Start End Blocks Id System
/dev/sda1 * 2048 499711 248832 83 Linux
/dev/sda2 501758 10483711 4990977 5 Extended
/dev/sda5 501760 10483711 4990976 8e Linux LVM
Disk /dev/sdb: 5368 MB, 5368709120 bytes
255 heads, 63 sectors/track, 652 cylinders, total 10485760 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000
Device Boot Start End Blocks Id System
/dev/sdb1 * 2048 499711 248832 fd Linux raid autodetect
/dev/sdb2 501758 10483711 4990977 5 Extended
/dev/sdb5 501760 10483711 4990976 fd Linux raid autodetect
Disk /dev/mapper/server1-root: 4563 MB, 4563402752 bytes
255 heads, 63 sectors/track, 554 cylinders, total 8912896 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000
Disk /dev/mapper/server1-root doesn't contain a valid partition table
Disk /dev/mapper/server1-swap_1: 532 MB, 532676608 bytes
255 heads, 63 sectors/track, 64 cylinders, total 1040384 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000
Disk /dev/mapper/server1-swap_1 doesn't contain a valid partition table
[email protected]:~#
To make sure that there are no remains from previous RAID installations on /dev/sdb, we run the following commands:
mdadm --zero-superblock /dev/sdb1
mdadm --zero-superblock /dev/sdb5
If there are no remains from previous RAID installations, each of the above commands will throw an error like this one (which is nothing to worry about):
[email protected]:~# mdadm --zero-superblock /dev/sdb1
mdadm: Unrecognised md component device - /dev/sdb1
[email protected]:~#
Otherwise the commands will not display anything at all.
