friends-of-tutorials/xen-software-raid

How to install a software raid on xen 7.6.2

XenServer 7.6.2 Software RAID installation (mdadm)

This instruction was written and tested for the XenServer version 7.6.2 and installs a software RAID (mdadm) afterwards. Thanks to the following discussion: https://discussions.citrix.com/topic/378478-xenserver-7-raid1-mdadm-after-install-running-system/ This instruction is based on it and has been adapted to version 7.6.2 in this manual:

1. Instruction

1.1 Installation of XenServer

First of all install the XenServer as usual without (!) the LVM repositories. Make sure that there are no mdadm-superblocks of older installations on the hard disk, because it is not possible to install XenServer on such disks. Use the following commands to clean up the partitions if necessary:

root$ umount /dev/md<number of md>
root$ mdadm --stop /dev/md<number of md>
root$ mdadm --zero-superblock /dev/sda<number of partition>

1.2 Install mdadm

1.2.1 Check environment after XenServer installation

We do have 5 partitions (sda1, sda2, sda3, sda5 and sda6):

root$ lsblk 
NAME   MAJ:MIN RM   SIZE RO TYPE MOUNTPOINT
sda      8:0    0 931,5G  0 disk 
├─sda1   8:1    0    18G  0 part /
├─sda2   8:2    0    18G  0 part 
├─sda3   8:3    0   512M  0 part 
├─sda5   8:5    0     4G  0 part /var/log
└─sda6   8:6    0     1G  0 part [SWAP]
sdb      8:32   0 931,5G  0 disk 
sdc      8:32   0 931,5G  0 disk 
sdd      8:48   0 931,5G  0 disk 
sr0     11:0    1  1024M  0 rom  
loop0    7:0    0    44M  1 loop /var/xen/xc-install

1.2.2 Load kernel module

root$ modprobe md_mod
root$ modprobe raid1

1.2.3 Delete partition informations on /dev/sdb

root$ sgdisk --zap-all /dev/sdb
root$ sgdisk --mbrtogpt --clear /dev/sdb

Make sure that there are no mdadm-superblocks of older installations on the hard disk. Use the following commands to clean up the partitions if necessary:

root$ umount /dev/md<number of md>
root$ mdadm --stop /dev/md<number of md>
root$ mdadm --zero-superblock /dev/sdb<number of partition>

1.2.4 Copy the partition table from /dev/sda to /dev/sdb

root$ sgdisk -R /dev/sdb /dev/sda

1.2.5 Set partition types

root$ sgdisk --typecode=1:fd00 /dev/sdb
root$ sgdisk --typecode=2:fd00 /dev/sdb
root$ sgdisk --typecode=3:ef02 /dev/sdb
root$ sgdisk --typecode=5:fd00 /dev/sdb
root$ sgdisk --typecode=6:fd00 /dev/sdb

1.2.6 Create RAID with /dev/sdb

root$ yes|mdadm --create /dev/md0 --level=1 --raid-devices=2 /dev/sdb1 missing
root$ yes|mdadm --create /dev/md1 --level=1 --raid-devices=2 /dev/sdb2 missing
root$ yes|mdadm --create /dev/md2 --level=1 --raid-devices=2 /dev/sdb3 missing
root$ yes|mdadm --create /dev/md4 --level=1 --raid-devices=2 /dev/sdb5 missing
root$ yes|mdadm --create /dev/md5 --level=1 --raid-devices=2 /dev/sdb6 missing

1.2.6.1 Check RAID

root$ cat /proc/mdstat 
Personalities : [raid1] 
md5 : active raid1 sdb6[0]
     1047552 blocks super 1.2 [2/1] [U_]
     
md4 : active raid1 sdb5[0]
     4190208 blocks super 1.2 [2/1] [U_]
     
md2 : active raid1 sdb3[0]
     523712 blocks super 1.2 [2/1] [U_]
     
md1 : active raid1 sdb2[0]
     18857984 blocks super 1.2 [2/1] [U_]
     
md0 : active raid1 sdb1[0]
     18857984 blocks super 1.2 [2/1] [U_]
     
unused devices: <none>

1.2.7 Create the filesystem

root$ mkfs.ext3 /dev/md0
root$ mkfs.ext3 /dev/md4
root$ mkswap /dev/md5

1.2.7.1 Check the filesystem

root$ lsblk 
NAME    MAJ:MIN RM   SIZE RO TYPE  MOUNTPOINT
sda       8:0    0 931,5G  0 disk  
├─sda1    8:1    0    18G  0 part  /
├─sda2    8:2    0    18G  0 part  
├─sda3    8:3    0   512M  0 part  
├─sda5    8:5    0     4G  0 part  /var/log
└─sda6    8:6    0     1G  0 part  [SWAP]
sdb       8:16   0 931,5G  0 disk  
├─sdb1    8:17   0    18G  0 part  
│ └─md0   9:0    0    18G  0 raid1 
├─sdb2    8:18   0    18G  0 part  
│ └─md1   9:1    0    18G  0 raid1 
├─sdb3    8:19   0   512M  0 part  
│ └─md2   9:2    0 511,4M  0 raid1 
├─sdb5    8:21   0     4G  0 part  
│ └─md4   9:4    0     4G  0 raid1 
└─sdb6    8:22   0     1G  0 part  
  └─md5   9:5    0  1023M  0 raid1 
sr0      11:0    1  1024M  0 rom   
loop0     7:0    0    44M  1 loop  /var/xen/xc-install

1.2.8 Mount the directories of /dev/sdb for preparation

root$ mount /dev/md0 /mnt
root$ mkdir -p /mnt/var/log
root$ mount /dev/md4 /mnt/var/log

1.2.9 Clone data to raid devices from /dev/sda to /dev/sdb

root$ cp -xa / /mnt
root$ cp -xa /var/log /mnt/var

1.2.10 create mdadm config

root$ echo "MAILADDR root" > /mnt/etc/mdadm.conf
root$ echo "auto +imsm +1.x -all" >> /mnt/etc/mdadm.conf
root$ echo "DEVICE /dev/sd*[a-z][1-9]" >> /mnt/etc/mdadm.conf
root$ mdadm --detail --scan >> /mnt/etc/mdadm.conf
root$ cp /mnt/etc/mdadm.conf /etc

1.2.10.1 Check the mdadm config

root$ cat /etc/mdadm.conf
MAILADDR root
auto +imsm +1.x -all
DEVICE /dev/sd*[a-z][1-9]
ARRAY /dev/md0 metadata=1.2 name=xenserver-7:0 UUID=b6eafb52:53b1c0ed:03b029cd:ce0fa6bf
ARRAY /dev/md1 metadata=1.2 name=xenserver-7:1 UUID=7b4bae54:236b1e2f:7f1a7a0e:e4610009
ARRAY /dev/md2 metadata=1.2 name=xenserver-7:2 UUID=0c082894:f0f24c6b:43bf4045:0970c253
ARRAY /dev/md4 metadata=1.2 name=xenserver-7:4 UUID=4a064db1:0c8e8f42:76810417:5cf0ecbd
ARRAY /dev/md5 metadata=1.2 name=xenserver-7:5 UUID=30dfc30a:1c8031bf:93d8c760:24186100

1.2.11 Set new fstab with md devices

1.2.11.1 Check the fstab config before adjustment

root$ cat /mnt/etc/fstab
LABEL=root-ocmtfp    /         ext3     defaults   1  1
LABEL=swap-ocmtfp          swap      swap   defaults   0  0
LABEL=logs-ocmtfp    /var/log         ext3     defaults   0  2
/opt/xensource/packages/iso/XenCenter.iso   /var/xen/xc-install   iso9660   loop,ro   0  0

1.2.11.2 Set new fstab

root$ sed -i 's/LABEL=root-[a-zA-Z\-]*/\/dev\/md0/' /mnt/etc/fstab
root$ sed -i 's/LABEL=swap-[a-zA-Z\-]*/\/dev\/md5/' /mnt/etc/fstab
root$ sed -i 's/LABEL=logs-[a-zA-Z\-]*/\/dev\/md4/' /mnt/etc/fstab
root$ cp /mnt/etc/fstab /etc

1.2.11.3 Check the fstab config after adjustment

root$ cat /mnt/etc/fstab
/dev/md0    /         ext3     defaults   1  1
/dev/md5          swap      swap   defaults   0  0
/dev/md4    /var/log         ext3     defaults   0  2
/opt/xensource/packages/iso/XenCenter.iso   /var/xen/xc-install   iso9660   loop,ro   0  0

1.2.12 Set label from sda to md0

root$ e2label /dev/sda1 |xargs -t e2label /dev/md0

1.2.13 Chroot the RAID to make some changes on it

root$ mount --bind /dev /mnt/dev
root$ mount --bind /sys /mnt/sys
root$ mount --bind /proc /mnt/proc
root$ chroot /mnt /bin/bash

1.2.14 Backup and build new initrd img

root$ cp /boot/initrd-$(uname -r).img /boot/initrd-$(uname -r).img.bak
root$ dracut --mdadmconf --fstab --add="mdraid" --add-drivers="raid1" --force /boot/initrd-$(uname -r).img $(uname -r) -M

1.2.15 Set grub configs and install grub loader on /dev/sdb

root$ sed -i 's/quiet/rd.auto rd.auto=1 rhgb quiet/' /boot/grub/grub.cfg
root$ sed -i 's/LABEL=root-[a-zA-Z\-]*/\/dev\/md0/' /boot/grub/grub.cfg
root$ sed -i '/search/ i\  insmod gzio part_msdos diskfilter mdraid1x' /boot/grub/grub.cfg
root$ sed -i '/search/ c\  set root=(md/0)' /boot/grub/grub.cfg
root$ grub-install /dev/sdb

1.2.16 Close chroot

root$ exit

1.2.17 Backup and copy the created initrd img and grub config

root$ cp /boot/initrd-$(uname -r).img /boot/initrd-$(uname -r).img.bak
root$ cp /mnt/boot/initrd-$(uname -r).img /boot/
root$ cp /mnt/boot/grub/grub.cfg /boot/grub/grub.cfg

1.2.18 Reboot the system (make sure to start with /dev/sdb!)

root$ reboot

1.2.19 Check if /dev/md2 is missing

root$ lsblk 
NAME    MAJ:MIN RM   SIZE RO TYPE  MOUNTPOINT
sda       8:0    0 931,5G  0 disk  
├─sda1    8:1    0    18G  0 part  /
├─sda2    8:2    0    18G  0 part  
├─sda3    8:3    0   512M  0 part  
├─sda5    8:5    0     4G  0 part  /var/log
└─sda6    8:6    0     1G  0 part  [SWAP]
sdb       8:16   0 931,5G  0 disk  
├─sdb1    8:17   0    18G  0 part  
│ └─md0   9:0    0    18G  0 raid1 
├─sdb2    8:18   0    18G  0 part  
│ └─md1   9:1    0    18G  0 raid1 
├─sdb3    8:19   0   512M  0 part  # <- /dev/md2 is missing
├─sdb5    8:21   0     4G  0 part  
│ └─md4   9:4    0     4G  0 raid1 
└─sdb6    8:22   0     1G  0 part  
  └─md5   9:5    0  1023M  0 raid1 
sr0      11:0    1  1024M  0 rom   
loop0     7:0    0    44M  1 loop  /var/xen/xc-install

If so then set fd00, create a new raid and check the uuid in /etc/mdadm.conf

root$ sgdisk --typecode=3:fd00 /dev/sdb
root$ yes|mdadm --create /dev/md2 --level=1 --raid-devices=2 /dev/sdb3 missing
root$ mdadm --detail --scan # vs.
root$ cat /etc/mdadm.conf
root$ vi /etc/mdadm.conf # change uuid if has changed

1.2.20 Delete partition informations on /dev/sda

root$ sgdisk --zap-all /dev/sda
root$ sgdisk --mbrtogpt --clear /dev/sda

1.2.21 Copy the partition table from sdb to sda

root$ sgdisk -R /dev/sda /dev/sdb

1.2.22 Complete raid

root$ mdadm -a /dev/md0 /dev/sda1
root$ mdadm -a /dev/md1 /dev/sda2
root$ mdadm -a /dev/md2 /dev/sda3
root$ mdadm -a /dev/md4 /dev/sda5
root$ mdadm -a /dev/md5 /dev/sda6

1.2.23 Check syncing RAID

root$ cat /proc/mdstat
Personalities : [raid1] 
md1 : active raid1 sda2[2] sdb2[0]
      18857984 blocks super 1.2 [2/2] [UU]
      
md4 : active raid1 sdb5[0] sda5[2]
      933114560 blocks super 1.2 [2/2] [UU]
      [=>...................]  resync =  7.2% (67247616/933114560) finish=136.2min speed=105941K/sec
      bitmap: 7/7 pages [28KB], 65536KB chunk
      
md5 : active raid1 sda6[2] sdb6[0]
      1047552 blocks super 1.2 [2/2] [UU]
      
md0 : active raid1 sdb1[0] sda1[2]
      18857984 blocks super 1.2 [2/2] [UU]
      
md2 : active raid1 sdb3[0] sda3[2]
      523712 blocks super 1.2 [2/2] [UU]
      
unused devices: <none>

Wait until the synchronization of all RAIDs is complete (md0 to md5). This may take a few hours. Continue afterwards.

1.2.24 Install grub on /dev/sda

root$ grub-install /dev/sda

1.2.25 Create LVM partitions on /dev/sda and /dev/sdb

root$ gdisk /dev/sda
n -> 4 -> ENTER -> ENTER -> FD00 -> w
root$ gdisk /dev/sdb
n -> 4 -> ENTER -> ENTER -> FD00 -> w

1.2.26 Create LVM RAID

root$ yes|mdadm --create /dev/md3 --level=1 --raid-devices=2 /dev/sda4 /dev/sdb4

1.2.27 Check partitions

root$ lsblk 
NAME    MAJ:MIN RM   SIZE RO TYPE  MOUNTPOINT
sda       8:0    0 931,5G  0 disk  
├─sda1    8:1    0    18G  0 part  
│ └─md0   9:0    0    18G  0 raid1 /
├─sda2    8:2    0    18G  0 part  
│ └─md1   9:1    0    18G  0 raid1 
├─sda3    8:3    0   512M  0 part  
│ └─md2   9:2    0 511,4M  0 raid1 
├─sda4    8:4    0   890G  0 part  
│ └─md3   9:3    0 889,9G  0 raid1 
├─sda5    8:5    0     4G  0 part  
│ └─md4   9:4    0     4G  0 raid1 /var/log
└─sda6    8:6    0     1G  0 part  
  └─md5   9:5    0  1023M  0 raid1 [SWAP]
sdb       8:16   0 931,5G  0 disk  
├─sdb1    8:17   0    18G  0 part  
│ └─md0   9:0    0    18G  0 raid1 /
├─sdb2    8:18   0    18G  0 part  
│ └─md1   9:1    0    18G  0 raid1 
├─sdb3    8:19   0   512M  0 part  
│ └─md2   9:2    0 511,4M  0 raid1 
├─sdb4    8:20   0   890G  0 part  
│ └─md3   9:3    0 889,9G  0 raid1 
├─sdb5    8:21   0     4G  0 part  
│ └─md4   9:4    0     4G  0 raid1 /var/log
└─sdb6    8:22   0     1G  0 part  
  └─md5   9:5    0  1023M  0 raid1 [SWAP]
sr0      11:0    1  1024M  0 rom   
loop0     7:0    0    44M  1 loop  /var/xen/xc-install

1.2.28 Check syncing RAID

root$ cat /proc/mdstat
Personalities : [raid1] 
md3 : active raid1 sdb4[1] sda4[0]
      933114560 blocks super 1.2 [2/2] [UU]
      [=>...................]  resync =  7.2% (67247616/933114560) finish=136.2min speed=105941K/sec
      bitmap: 7/7 pages [28KB], 65536KB chunk

md1 : active raid1 sda2[2] sdb2[0]
      18857984 blocks super 1.2 [2/2] [UU]
      
md4 : active raid1 sdb5[0] sda5[2]
      4190208 blocks super 1.2 [2/2] [UU]
      
md5 : active raid1 sda6[2] sdb6[0]
      1047552 blocks super 1.2 [2/2] [UU]
      
md0 : active raid1 sdb1[0] sda1[2]
      18857984 blocks super 1.2 [2/2] [UU]
      
md2 : active raid1 sdb3[0] sda3[2]
      523712 blocks super 1.2 [2/2] [UU]
      
unused devices: <none>

Wait until the synchronization is complete. This may take a few hours. Continue afterwards.

1.2.29 Make metadata readable and the lvmetad.socket available

root$ vi /etc/lvm/lvm.conf

Set metadata_read_only to 0 and use_lvmetad also to 0:

metadata_read_only = 0

use_lvmetad = 0

1.2.30 Create LVM

root$ pvcreate /dev/md3
  Physical volume "/dev/md6" successfully created
root$ xe sr-create type=lvm content-type=user device-config:device=/dev/md3 name-label="Local Storage 1"

1.3 Create another LVM Repository if wanted and add new disks

1.3.1 Create second LVM partitions on /dev/sdc and /dev/sdd

root$ gdisk /dev/sdc
n -> 4 -> ENTER -> ENTER -> FD00 -> w
root$ gdisk /dev/sdd
n -> 4 -> ENTER -> ENTER -> FD00 -> w

1.3.2 Create second LVM RAID

root$ yes|mdadm --create /dev/md6 --level=1 --raid-devices=2 /dev/sdc1 /dev/sdd1

1.3.3 Check sync status

Personalities : [raid1] 
md6 : active raid1 sdb4[1] sda4[0]
      933114560 blocks super 1.2 [2/2] [UU]
      [=>...................]  resync =  7.2% (67247616/933114560) finish=136.2min speed=105941K/sec
      bitmap: 7/7 pages [28KB], 65536KB chunk

md3 : active raid1 sdb4[1] sda4[0]
      933114560 blocks super 1.2 [2/2] [UU]
      bitmap: 0/7 pages [0KB], 65536KB chunk

md1 : active raid1 sda2[2] sdb2[0]
      18857984 blocks super 1.2 [2/2] [UU]
      
md4 : active raid1 sdb5[0] sda5[2]
      4190208 blocks super 1.2 [2/2] [UU]
      
md5 : active raid1 sda6[2] sdb6[0]
      1047552 blocks super 1.2 [2/2] [UU]
      
md0 : active raid1 sdb1[0] sda1[2]
      18857984 blocks super 1.2 [2/2] [UU]
      
md2 : active raid1 sdb3[0] sda3[2]
      523712 blocks super 1.2 [2/2] [UU]
      
unused devices: <none>

Wait until the synchronization is complete. This may take a few hours. Continue afterwards.

1.3.4 Check partitions

root$ lsblk 
NAME    MAJ:MIN RM   SIZE RO TYPE  MOUNTPOINT
sda       8:0    0 931,5G  0 disk  
├─sda1    8:1    0    18G  0 part  
│ └─md0   9:0    0    18G  0 raid1 /
├─sda2    8:2    0    18G  0 part  
│ └─md1   9:1    0    18G  0 raid1 
├─sda3    8:3    0   512M  0 part  
│ └─md2   9:2    0 511,4M  0 raid1 
├─sda4    8:4    0   890G  0 part  
│ └─md3   9:3    0 889,9G  0 raid1 
├─sda5    8:5    0     4G  0 part  
│ └─md4   9:4    0     4G  0 raid1 /var/log
└─sda6    8:6    0     1G  0 part  
  └─md5   9:5    0  1023M  0 raid1 [SWAP]
sdb       8:16   0 931,5G  0 disk  
├─sdb1    8:17   0    18G  0 part  
│ └─md0   9:0    0    18G  0 raid1 /
├─sdb2    8:18   0    18G  0 part  
│ └─md1   9:1    0    18G  0 raid1 
├─sdb3    8:19   0   512M  0 part  
│ └─md2   9:2    0 511,4M  0 raid1 
├─sdb4    8:20   0   890G  0 part  
│ └─md3   9:3    0 889,9G  0 raid1 
├─sdb5    8:21   0     4G  0 part  
│ └─md4   9:4    0     4G  0 raid1 /var/log
└─sdb6    8:22   0     1G  0 part  
  └─md5   9:5    0  1023M  0 raid1 [SWAP]
sdc       8:32   0 931,5G  0 disk  
└─sdc1    8:33   0 931,5G  0 part  
  └─md6   9:6    0 931,4G  0 raid1 
sdd       8:48   0 931,5G  0 disk  
└─sdd1    8:49   0 931,5G  0 part  
  └─md6   9:6    0 931,4G  0 raid1 
sr0      11:0    1  1024M  0 rom   
loop0     7:0    0    44M  1 loop  /var/xen/xc-install

1.3.5 Create second LVM

root$ pvcreate /dev/md6
  Physical volume "/dev/md6" successfully created
root$ xe sr-create type=lvm content-type=user device-config:device=/dev/md6 name-label="Local Storage 2"

1.4 Setting up email notification

1.4.1 Install a MTA (postfix)

1.4.1.1 Enable CentOS repository

root$ vi /etc/yum.repos.d/CentOS-Base.repo

Set enabled to 1:

[base]
name=CentOS-$releasever - Base
mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=os&infra=$infra
enabled=1

1.4.1.2 Install and configure postfix

root$ yum install postfix mailx

Edit some postfix configs:

root$ vi /etc/postfix/main.cf

inet_interfaces = 127.0.0.1, 192.168.18.10

1.4.1.3 Start postfix

root$ postfix start

1.4.1.4 sSMTP configuration

root$ vi /etc/ssmtp/ssmtp.conf

Set mailhub to localhost:

mailhub=127.0.0.1

root$ vi /etc/ssmtp/revaliases

root:your@email-sender-address.tld

1.4.1.4 Disable CentOS repository again

root$ vi /etc/yum.repos.d/CentOS-Base.repo

Set enabled to 0:

[base]
name=CentOS-$releasever - Base
mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=os&infra=$infra
enabled=0

1.4.1 Check the mail command

root$ echo "Add some text in here" | mail -s "The subject of this email" <email@address.tld>

1.5 Check RAID health status manually

root$ cat /proc/mdstat

1.5.1 An example of a fully functional RAID

Personalities : [raid1] 
md6 : active raid1 sdd1[1] sdc1[0]
      976630464 blocks super 1.2 [2/2] [UU]
      bitmap: 0/8 pages [0KB], 65536KB chunk

md3 : active raid1 sdb4[1] sda4[0]
      933114560 blocks super 1.2 [2/2] [UU]
      bitmap: 0/7 pages [0KB], 65536KB chunk

md1 : active raid1 sda2[2] sdb2[0]
      18857984 blocks super 1.2 [2/2] [UU]
      
md4 : active raid1 sdb5[0] sda5[2]
      4190208 blocks super 1.2 [2/2] [UU]
      
md5 : active raid1 sda6[2] sdb6[0]
      1047552 blocks super 1.2 [2/2] [UU]
      
md0 : active raid1 sdb1[0] sda1[2]
      18857984 blocks super 1.2 [2/2] [UU]
      
md2 : active raid1 sdb3[0] sda3[2]
      523712 blocks super 1.2 [2/2] [UU]
      
unused devices: <none>

1.5.2 An example of a defective RAID

In progress..

1.6 Change a defective hard disk

In progress..

A. Authors

• Björn Hempel bjoern@hempel.li - Initial work - https://github.com/bjoern-hempel

B. Licence

This tutorial is licensed under the MIT License - see the LICENSE.md file for details

C. Closing words

Have fun! :)